Has Anyone Seen A Realistice Explanation For Free Fall Of The Towers?

[T.A.M.]

The aircraft was going 800 kilometres per hour (not second). Which is about 222m/s which is about 670 feet per second.

At a frame rate of 1 fps, the camera would be lucky to catch a glimpse of the plane in any of the 5 frames (at 1fps, 5 frames = 5 seconds, in which the plane would have moved a full 1100m or 3350 feet.)

TAM

[apathoid]

You originally wrote:


Whats to calculate? 1 frame per second, not 25. A plane moving at 530 mph or 780 feet/sec will travel 780 feet, or 5 fuselage lengths, between security camera frames..

ETA: thats at 90 degrees, since the plane hit close to a 45 degree angle, then I believe it would be .707x780 ft..

[Arkan_Wolfshade]

Could you calculate the speed for me then, I'm lost

For one 850 (kilometers / second) = 1,901,395.85 mph. I don't think the plane was going that fast. Memory is that the plane was at ~580 mph. So:
580 mph => 0.161111111 miles per second
=> 850.666666 feet per second

A Boeing 757-223 (which is what Flight 77 was) is 155 ft 3 in (47.32 m) long.
So, in 1 second it travels ~5.4793344025764895330112721417069 times its length.

If someone knows the field of view of the camera, I'm sure we can calculate the possibilities of:
1) The plane being in the picture at all
2) The entire plane being in the picture

[Skibum]

I also don't get this, this is the Pentagon not McDonald's or the whammyburger.

The thing is, we are talking about the government. I've seen ancient security cameras used in some very high security places.

They don't upgrade them every other year, they could have been 20 year old cameras.

Sure new cameras are cheap and take great pictures, but unless the camera was broken chances are it would not have been replaced.

[Arkan_Wolfshade]

The thing is, we are talking about the government. I've seen ancient security cameras used in some very high security places.

They don't upgrade them every other year, they could have been 20 year old cameras.

Sure new cameras are cheap and take great pictures, but unless the camera was broken chances are it would not have been replaced.

Plus, it is there to take pictures of the cars that are stopped at the security gate, not to take pictures of objects travelling 4x faster than most cars top out at.

[Oliver]

While talking about the pentagon:

I allready posted this to LCF some days ago.

Did someone in here saw a colored version of this rare photo,
showing something that the idaho observer describes as
plane-wings in their printed version on June 2006:

The article: (without photos)
http://www.proliberty.com/observer/20060607.htm

The related photo: (scanned b/w)
http://www.voicesofsafety.com/pogonews/2006/images/2006-08-08-IO-Article-pic-1.jpg

The thread at LCF:
http://s15.invisionfree.com/Loose_Change_Forum/index.php?showtopic=12185

Regards,
Oliver

[kevin]

I also don't get this, this is the Pentagon not McDonald's or the whammyburger.

That's exactly why they fooled themselves into thinking they didn't need them "we're the freaking Pentagon, who's going to attack us?".

The Pentagon is a huge bureaucracy, the budgets for these kind of low "cool factor" technology gets stripped and put into "necessary" projects like trying to kill goats with your mind (or was that the CIA?)

[einsteen]

I mean of course /h instead of /s, typo..

Ok with 1 fps I calculated a chance of 50% to get one plane uncrashed in one frame, realistic.

That site I posted at top does some analysis too (also 3d), the guy thinks they removed one frame.

[rwguinn]

The thing is, we are talking about the government. I've seen ancient security cameras used in some very high security places.

They don't upgrade them every other year, they could have been 20 year old cameras.

Sure new cameras are cheap and take great pictures, but unless the camera was broken chances are it would not have been replaced.

There is also the fact that a parking lot camera is not used for any purpose other than detecting events which are moving at a walking pace, or suspicious individuals cruising the lot at 15-20mph (up to maybe 30 feet/sec). Given the field of view, at that speed, one or more frames will catch them.
(Cruisers at higher speeds in the lot are likely to attract other attention, in case you're wondering)
Who expects a 500+ mph problem?

[Oliver]

GENERAL QUESTION:

Did anyone see a structural, internal blueprint
of the towers regarding the elevatorshafts and
their arrangement in (horizontal and vertical) and/or
(perspective) view?

Maybe in some books? I can´t find any visual
information in form of illustrations about the
buildings internal structure.

BTW: Or WTC7?

Regards,
Oliver

[Arkan_Wolfshade]

I mean of course /h instead of /s, typo..

Ok with 1 fps I calculated a chance of 50% to get one plane uncrashed in one frame, realistic.

That site I posted at top does some analysis too (also 3d), the guy thinks they removed one frame.

Sorry, statistics are not my strong suit; how did you come to the 50% chance?

[T.A.M.]

Impossible to calculate the chance of capturing it in a frame, without knowing the exact distance from left to right that is covered by the frame for the given path of the aircraft.

TAM

[Arkan_Wolfshade]

GENERAL QUESTION:

Did anyone see a structural, internal blueprint
of the towers regarding the elevatorshafts and
their arrangement in (horizontal and vertical) and/or
(perspective) view?

Maybe in some books? I can´t find any visual
information in form of illustrations about the
buildings internal structure.

BTW: Or WTC7?

Regards,
Oliver

There are some diagrams in the NIST/FEMA reports, but the actual blueprints are the property of the Port Authority, which has not released them. This is something some of the deniers harp about as being evidence of a conspiracy.

[kevin]

While talking about the pentagon:


You seen these photos? Click on an image takes you to the high res version.

http://www.geoffmetcalf.com/pentagon/pentagon_20020316.html

This one show small debris from the plane scattered all over.
http://www.geoffmetcalf.com/pentagon/images/11.jpg

bigger chunk of airplane debris
http://www.geoffmetcalf.com/pentagon/images/13.jpg

[apathoid]

Impossible to calculate the chance of capturing it in a frame, without knowing the exact distance from left to right that is covered by the frame for the given path of the aircraft.

TAM

You could ball park it though by comparing the camera stills to the known approximate flight path against an aerial photo(or Google Earth) and measuring the far right of the screen to the impact point. The problem is not knowing exactly when the shutter is closing in each of the frames...therefore its not possible to calculate the odds of the entire plane being in the frame..

[Oliver]

You seen these photos? Click on an image takes you to the high res version.

http://www.geoffmetcalf.com/pentagon/pentagon_20020316.html

This one show small debris from the plane scattered all over.
http://www.geoffmetcalf.com/pentagon/images/11.jpg

bigger chunk of airplane debris
http://www.geoffmetcalf.com/pentagon/images/13.jpg

*Thank you, Kevin.

I´ve already studied your photos. I try to find more
information about what type of Plane it was, based
on pieces of the outer hull.

Did you see that Photo i mentioned once earlier?

*To Arkan:

Thanks for your help. I´m trying to learn more about
the positions of the elevators. The best case would
be a threedimensional illustration to understand it´s
internal construction. The Nist Illustrations do not
work to get this grasp.

Thanks anyway. :)

[apathoid]

*Thank you, Kevin.

I´ve already studied your photos. I try to find more
information about what type of Plane it was, based
on pieces of the outer hull.


Hi Oliver, welcome to the forum.




Here is a great shot if the little "c" in "American" title.
http://911myths.com/html/pentagon_16.html

Here is a good one of the main landing gear wheel assembly
http://911myths.com/html/pentagon_3.html

Is this what you are looking for?

[kevin]

GENERAL QUESTION:

Did anyone see a structural, internal blueprint
of the towers regarding the elevatorshafts and
their arrangement in (horizontal and vertical) and/or
(perspective) view?

Maybe in some books? I can´t find any visual
information in form of illustrations about the
buildings internal structure.

BTW: Or WTC7?

Regards,
Oliver

i've got some plan view ones somewhere on one of the towers, I'll see if i can dig them up. Note that not all elevators served all floors so there are floors where some shafts have doors on certain floors and some don't.

the WTC wikipedia article has a representation of the vertical but it's not to scale, it just shows some of the elevators that served particular floors.

[Arus808]

Hey all, haven't read the entire thread (I just got over reading the four threads about Loose Change), but a "truther" im arguing with is stuck on the "buildings fell at free fall speeds" despite my insistance they didn't .

Anyone have a much more "clinical" analysis of the falls of the towers to prove they did not fall at free fall speeds?

Of course, this truther is also using the scholars for truth website, and relying on their claims.

[Oliver]

Hi Oliver, welcome to the forum.

He is a great shot if the little "c" in "American" title.
http://911myths.com/assets/images/db_images/db_Pentagon_Debris_171.jpg

Here is a good one of the main landing gear wheel assembly
http://911myths.com/assets/images/db_images/db_Pentagon_Debris_111.jpg

Is this what you are looking for?

Hello apathoid,

the links don´t work (forbidden) but i think i guess the
pictures you referred.

I´m actually trying to find more evidence about this
scanned picture wich was posted in the Idaho Observer.
Did you see it once earlier - somewhere?
Link:
http://www.voicesofsafety.com/pogonews/2006/images/2006-08-08-IO-Article-pic-1.jpg

[apathoid]

Hey all, haven't read the entire thread (I just got over reading the four threads about Loose Change), but a "truther" im arguing with is stuck on the "buildings fell at free fall speeds" despite my insistance they didn't .

Anyone have a much more "clinical" analysis of the falls of the towers to prove they did not fall at free fall speeds?

Of course, this truther is also using the scholars for truth website, and relying on their claims.

Just find any photo of the collapse in progress and ask them why the debris is falling faster than the building itself...and if the debris is falling faster than freefall. They dont like that argument, but they havent been able to counter it yet.

[Arus808]

Just find any photo of the collapse in progress and ask them why the debris is falling faster than the building itself...and if the debris is falling faster than freefall. They dont like that argument, but they havent been able to counter it yet.

I did, but he basically ignores it, because its not "scientific" enough for him his excuse is that they were "jetisoned" by explosions, so they were going to travel faster to the ground because of the force .

[Oliver]

i've got some plan view ones somewhere on one of the towers, I'll see if i can dig them up. Note that not all elevators served all floors so there are floors where some shafts have doors on certain floors and some don't.

the WTC wikipedia article has a representation of the vertical but it's not to scale, it just shows some of the elevators that served particular floors.

Hello Kevin, this would be wonderful if you find these Illustrations. :)

[apathoid]

Hello apathoid,

the links don´t work (forbidden) but i think i guess the
pictures you referred.

I´m actually trying to find more evidence about this
scanned picture wich was posted in the Idaho Observer.
Did you see it once earlier - somewhere?
Link:
http://www.voicesofsafety.com/pogonews/2006/images/2006-08-08-IO-Article-pic-1.jpg

Hmmm, they work for me. Try refreshing the page after you click the links.

Wow, I've never seen that shot before. To me, the only part of the airplane they could possibly be are the spoilers; those are the only perfectly flat squarish parts of the airplane that I can think of...

[Oliver]

I may have an interesting idea about
the bombs-story.

Maybe it´s proofable if there where bombs
or not. William Rodriguez talked (and (s)ome
others i dont remind) about the elevator doors,
wich were blown open.

Working 20 Years in the Building, William and
other people should remind which specific
elevator doors were blown.

If not all elevators did reach entireley to the
floors where the planes hit, these doors
should´nt have been blown during the
fireball walking down the shafts, am i right?

It would be helpfull to have blueprints or
someone who knows the towers like Willi.

Regards,
Oliver

*Posted as general, new thread*

[apathoid]

I did, but he basically ignores it, because its not "scientific" enough for him his excuse is that they were "jetisoned" by explosions, so they were going to travel faster to the ground because of the force .

You could find a popular youtube/google video clip that shows the collapses in their entirety and record the start and stop times of the collapse, I usally get anywhere from 12-16 seconds...

[Oliver]

Hmmm, they work for me. Try refreshing the page after you click the links.

Wow, I've never seen that shot before. To me, the only part of the airplane they could possibly be are the spoilers; those are the only perfectly flat squarish parts of the airplane that I can think of...

Mhmm, i cleared my cache, cookies and reloaded,
it does not work for me:

"Forbidden
You don't have permission to access /assets/images/db_images/db_Pentagon_Debris_171.jpg on this server."

[apathoid]

I may have an interesting idea about
the bombs-story.

Maybe it´s proofable if there where bombs
or not. William Rodriguez talked (and (s)ome
others i dont remind) about the elevator doors,
wich were blown open.

Working 20 Years in the Building, William and
other people should remind which specific
elevator doors were blown.

If not all elevators did reach entireley to the
floors where the planes hit, these doors
should´nt have been blown during the
fireball walking down the shafts, am i right?

It would be helpfull to have blueprints or
someone who knows the towers like Willi.

Regards,
Oliver

You're correct, of course. I'm not certain of this and I think this topic has been covered here before - but there were only 2 elevators that went all the way up to the top from the basement; the utility elevators. I'll see if I can find a link.

[apathoid]

Mhmm, i cleared my cache, cookies and reloaded,
it does not work for me:

"Forbidden
You don't have permission to access /assets/images/db_images/db_Pentagon_Debris_171.jpg on this server."

Ok, I gave you bad links - they work for me for some reason.

http://911myths.com/html/pentagon_16.html
http://911myths.com/html/pentagon_3.html

[Oliver]

You're correct, of course. I'm not certain of this and I think this topic has been covered here before - but there were only 2 elevators that went all the way up to the top from the basement; the utility elevators. I'll see if I can find a link.

Ops - i thought it was new. :">
I also try to find the thread...

[Arus808]

You could find a popular youtube/google video clip that shows the collapses in their entirety and record the start and stop times of the collapse, I usally get anywhere from 12-16 seconds...

I did, but he is using some other "timing" device, because he says its 10 seconds (as stated in the NIST report which they stated 11 seconds for WTC 1 and 9 seconds for WTC 2). However, I need a more " conclusive " clicnial analysis cause he doesn't belive that its NOT free fall. Considering that the buidling would have to fall in 8.2 seconds to be even considered freefall (anyone want to offer up why 10 seconds isn't free fall?)

[TjW]

Hmmm, they work for me. Try refreshing the page after you click the links.

Wow, I've never seen that shot before. To me, the only part of the airplane they could possibly be are the spoilers; those are the only perfectly flat squarish parts of the airplane that I can think of...

It looks to me like those are parts of the main wing spar that have been cut into sections to make it easier to remove.
Note that it is quite thick along the longer sides -- the "spar caps". The thin plate between the caps is the shear web

[Oliver]

Ops - i thought it was new. :">
I also try to find the thread...

Thank you, apathoid.

I already know these pictures, but CT´s think
the hull piece is no evidence and it´s to "thin"
to them to belong to a Boing.

[T.A.M.]

ARUS808:
Welcome to the JREF Skeptics Forum on Conspiracy Theories.

The fastest that a falling body (a body that starts from rest, with only gravity acting on it in the downward direction) can travel is "Free Fall" speed. This occurs only when an object is dropped from within a vacuum ,with no air resistance.

If the debris that falls along side the twin towers as they collapse are falling faster than the towers themselves, than the towers cannot be collapsing at Freefall speed because (1) It isnt taking place in a vacuum, and (2) There are items falling faster (the debris), and the fastest the debris could be going is not even free fall (not in a vacuum either).

Now to the above, they will certainly argue a "Strawman", meaning that No "serious" CTer actually believes the towers fell "at" Free Fall speed.

To this I would say, that there is some evidence that the towers fell at near "Freefall" speed, though even this is contraversial.

If they then ask, well how did the towers fall at "near" free fall speed despite all the resistance that should have slowed the fall from the building below, I would reply...

"As NIST has stated, once the collapse was intitiated at the site of impact, the level of energy produced through the fall of the tower above the impact zone, down onto the remainder of the building below was of such a large magnitude as to make the resistance of the floors beneath negligible in comparison, and so the towers came down in a progressive, near resistance free fashion, allowing it to fall at said "near" free fall speed.

but thats just me...

TAM

[apathoid]

It looks to me like those are parts of the main wing spar that have been cut into sections to make it easier to remove.
Note that it is quite thick along the longer sides -- the "spar caps". The thin plate between the caps is the shear web

You could be right, I have no idea what the spars look like(except the aft spar) on a 757. If this photo was in color and wasnt so grainy - it'd be an easy identification. But, these parts have a composite appearance to me for some reason and color(lightness) would be about right for spoiler panels. Also, on the underside of the panels, there is weatherproofing frame(left object) that isnt evident from the top(right object)
Its hard to judge the size of these things though. To me, it looks like around 2X6 ft.

I already know these pictures, but CT´s think
the hull piece is no evidence and it´s to "thin"
to them to belong to a Boing.

Well, they are wrong. The outer skin on Boeings is typically 0.063 inches, or about 2 millimeters.

[kevin]

edit: moved to other thread

[Belz...]

I also don't get this, this is the Pentagon not McDonald's or the whammyburger.

Why would you need a 20-frame per second camera to watch over cars, einsteen ?

[Belz...]

Hey all, haven't read the entire thread

Boy, are you in for a treat!

[Belz...]

The fastest that a falling body (a body that starts from rest, with only gravity acting on it in the downward direction) can travel is "Free Fall" speed. This occurs only when an object is dropped from within a vacuum ,with no air resistance.

I wasn't aware that free fall was a speed. I thought it was a falling "mode".

Now to the above, they will certainly argue a "Strawman", meaning that No "serious" CTer actually believes the towers fell "at" Free Fall speed.

Wouldn't they then be guilty of a No True Scottsman ?

[einsteen]

Sorry, statistics are not my strong suit; how did you come to the 50% chance?

The height of the pentagon is known, I took this picture (without having read the site from which it is http://www.montalk.net/pentagon.html)

http://www.montalk.net/composite.jpg

L then is about 400 feet (I don't use feet normally)
assume a speed of 800 feet/sec (which means each frame the object travels a distance 2L) and ignore the yellow thing

then the chance that a plane with length 0<=l<L is captured (at least one part of it intersects with L) is 50%.
As fas as I can see it is independent of the length, but if l=>L then the
chance is 100% because then there is always at least a part captured although it can be a point of it

To be precise also the chance that the object is precisely in the middle not touching the left or right side needs to be calculated, it's too late for me and probably I have to get some books out of the dust, it's been a while, but that chance must be much lower.

[einsteen]

Hello apathoid,

the links don´t work (forbidden) but i think i guess the
pictures you referred.


If you use IE and the link does not work then drag and drop the link to the address bar, it is a http-referer issue in this case

[T.A.M.]

Belz:

Sorry Dark Master, "Free Fall" speed as I explained it is probably more of a velocity, as it has a direction (down). "Free Fall", I believe, refers to the lack of resistance applied against the falling body.

Einsteen:
I can see where you are getting the number. For any given frame, the chance of seeing "any part of the plane, "Somewhere" in the frame, would be about 50%.

I believe, they did catch the tail section in one of the frames, but it is such a poor quality picture, that people argue about what they are seeing it all the time.

TAM

[Oliver]

Well, they are wrong. The outer skin on Boeings is typically 0.063 inches, or about 2 millimeters.

:D Try to tell them for yourself. I did - thats why i´m here. :D

[apathoid]

:D Try to tell them for yourself. I did - thats why i´m here. :D

I'd love to, but I've been IP banned ;)

[einsteen]

I'd love to, but I've been IP banned ;)

ironic mode I assume, because an IP doesn't say anything in the time where there are free proxy lists available

[apathoid]

ironic mode I assume, because an IP doesn't say anything in the time where there are free proxy lists available

I really have no desire to jump through hoops to view the Loose Change forums. But even if I did, I can't post because my account is suspended until 2009.

[Metullus]

I really have no desire to jump through hoops to view the Loose Change forums. But even if I did, I can't post because my account is suspended until 2009.What day in 2009? Maybe we should start a count-down to give you something to live for...

[Pardalis]

What day in 2009? Maybe we should start a count-down to give you something to live for...

Let's hope this 9/11 denial nonsense will have died out.

[Oliver]

General Question:

Can somebody in here who is very familiar with
the 2 Towers inner structure like the elevator-
shafts, help me with this tread? :

http://forums.randi.org/showthread.php?t=63409

Or do you know who is/are the most educated
person/s in here regarding the towers?

Regards,
Oliver

[Metullus]

Let's hope this 9/11 denial nonsense will have died out.Optimistic sort, aren't you?

[Christophera]

General Question:

Can somebody in here who is very familiar with
the 2 Towers inner structure like the elevator-
shafts, help me with this tread? :

http://forums.randi.org/showthread.php?t=63409

Or do you know who is/are the most educated
person/s in here regarding the towers?

Regards,
Oliver

Would you be referring to the towers that actually stood or the towers that officially collapsed.

[delphi_ote]

Would you be referring to the towers that actually stood or the towers that officially collapsed.
Is there a difference between the two?

[Brainache]

NOOOOOOOOO!!!!!!

3"rebar 4'centres repeat until head explodes...

[Christophera]

Is there a difference between the two?

The one that officially collapsed could not have stood, and if it did and collapsed or was demoed, the official core would be seen in the images. It is not and posters here have proven it by failing to produce images of the official core at elevation from the images.

This thread has the proof. What is it, 83 pages now? Not one obvious image of the official core can be found. All that is found in support of the official core are a plethora of misinterpreted constructon images and 2 misinterpreted demo images.

The other 99% of the thread is littered with images showing the true core of the towers and lnks to the site dedicated to sharing it.

http://concretecore.741.com

Or the only site on the web that explains near free fall and total pulverization.

http://algoxy.com/psych/9-11scenario.html.

The other posters here have dedicated their efforts to obliterating the true tower design because it helps explain what was seen.

exploding concrete (http://algoxy.com/psych/images/corefacesexploding.jpg)

[Z]

Ignore Chris - he's a liar.

[Belz...]

Belz:

Sorry Dark Master, "Free Fall" speed as I explained it is probably more of a velocity, as it has a direction (down). "Free Fall", I believe, refers to the lack of resistance applied against the falling body.

Well, someone's going to have to clarify this, because if "free fall" refers to a speed, I'd like to know which one. Gravity tends to accelerate bodies, so unless you reach terminal velocity, your speed is increasing, and therefore not constant. "Free fall" speed would therefore be variable, and hence useless.

[twinstead]

I have never seen anybody tie up a thread for so long with such an untenable position.

Chris my hat is off to you. You don't have a leg to stand on, logically or factually, yet you continue to press your point with the tenacity that only a severly deluded person could muster.

I guess you at least stay true to yourself. Bravo.

[Belz...]

Would you be referring to the towers that actually stood or the towers that officially collapsed.

How does that relate to his elevator and structure question ?

The one that officially collapsed could not have stood, and if it did and collapsed or was demoed, the official core would be seen in the images. It is not and posters here have proven it by failing to produce images of the official core at elevation from the images.


And, by that logic, if it were true, and since you haven't produced the concrete core in any clear way, what we have to conclude is that:

The WTC had NO core!

[Architect]

Ignore Chris - he's a liar.

And a fool

[Cuddles]

Would you be referring to the towers that actually stood or the towers that officially collapsed.

There were four towers now?

[Stellafane]

...The other posters here have dedicated their efforts to obliterating the true tower design because it helps explain what was seen.,,

Christophera, you are a proven liar.

The only question that now remains concerning you is, why should anyone even bother to respond to a proven liar? Until you can provide some sort of answer, I don't see why anyone should dignify anything you write with a reply.

This isn't something you can ignore, Chris. You now stand as a liar, and thus have zero credibility. Therefore everything you post can and should be completely dismissed.

[Matthew Best]

Ok, so no change there.

[einsteen]

@Christopera

in the 911eyewitness video at 38min20sec you can see some elements falling after the collapse like mikado sticks. I don't know what this means because I'm no construction specialist, I've cropped that part (aspect ratio and framerate not changed) and it's at

http://www.youtube.com/watch?v=wkvnGsDm34M

[CurtC]

Looks like Christophera has someone to agree with him over at the LC Forums:

Has anyone bothered to get the blueprints? This whole debate could be moot if someone just checks the blueprints. Im inclined to think it does/did have a concrete core. I remember reading a website a while back with all kinds of quotes from Structural Engineers, Designers of the WTC, et al. All of them referenced a steel reinforced concrete core. I'll see if i can find it.

[chipmunk stew]

Looks like Christophera has someone to agree with him over at the LC Forums:
Ooh, man, someone's gotta provide him with those algoxy (or whatever) links!

[Mancman]

@Christopera

in the 911eyewitness video at 38min20sec you can see some elements falling after the collapse like mikado sticks. I don't know what this means because I'm no construction specialist, I've cropped that part (aspect ratio and framerate not changed) and it's at

http://www.youtube.com/watch?v=wkvnGsDm34M

It's a bundle of core columns. The same section that christophera continually mislabels are 'interior box columns'.

[T.A.M.]

Belz:

If my college physics serves me correctly, you are correct. The speed the bodies would travel would accelerate until they reached "Terminal Velocity" I would imagine that at some point this occured, given the height of the buildings.

Interesting, because the CTers always refer to it as "Free Fall" speed...so much so that I misspoke it myself (even bumbling on the science by calling it a velocity, although i guess it was a sequence of increasing velocities until terminal velocity was reached, and then it was a constant velocity).

My apologies Dark Lord...but you are right, we should get clarification from one of the CTers as to why they refer to it as Free Fall "Speed" which does not even count for the direction of the motion, let alone the application of the acceleration.

TAM

[GlennB]

Belz:
My apologies Dark Lord...but you are right, we should get clarification from one of the CTers as to why they refer to it as Free Fall "Speed" which does not even count for the direction of the motion, let alone the application of the acceleration.

TAM

"free fall speed" is a slightly unscientific way of describing a real phenomenon.

An object "free falling" in a vacuum will reach a certain speed after x seconds of travel. Routine school equations apply here.

Add resistance (air) and smaller/lighter items will not reach so-called "free-fall" speeds because of friction. They may in fact reach terminal velocity, where increasing frictional force equals gravitational force.

A sideways element to the direction of travel (for example a bullet fired from a gun) has no effect on earthward movement (always bearing in mind the vacuum part of the discussion) That is - if you simultaneously drop + fling balls from a cliff they wil hit the ground at the same time. The downward component of their motion is the same in both scenarios.

I don't have the science to state categorically that a steel girder wouldn't reach terninal velocity during a 400m fall. I'd seriously doubt it though, as people skydiving take a much greater fall than that to reach termnal velocity, and steel girders are much bigger and denser than people.

Regards

[einsteen]

Freefall speed, the speed of gravity, there are a lot of misunderstandings of course. I'm sure most people here will know Newtonian mechanics.

Each particle does nothing more than F=ma or F=dP/dt, with P=mv

If you consider the latter as the definition of Force then you can avoid a totally pointless discussion about what a force is.

Each particle wants to move to the middle of the earth with a force

F=GMmu/r^2, at the surface of the earth the excellent estimation F=mg can be used.

The formula at top is inertial mass, the other is gravitational mass, it seems to behave 1:1 (it looks maybe trivial but it isn't)

The acceleration a of a mass m in vacuum is a=dv/dt=(1/m)dP/dt=F/m=(mg)/m=g

When there is air there are other forces on the mass (always opposite to the direction in which it travels) which is the reason that free fall in air will reach a constant speed. This in fact means that the netto force on a falling body with constant speed is zero.

[Metullus]

Belz:

If my college physics serves me correctly, you are correct. The speed the bodies would travel would accelerate until they reached "Terminal Velocity" I would imagine that at some point this occured, given the height of the buildings.

Interesting, because the CTers always refer to it as "Free Fall" speed...so much so that I misspoke it myself (even bumbling on the science by calling it a velocity, although i guess it was a sequence of increasing velocities until terminal velocity was reached, and then it was a constant velocity).

My apologies Dark Lord...but you are right, we should get clarification from one of the CTers as to why they refer to it as Free Fall "Speed" which does not even count for the direction of the motion, let alone the application of the acceleration.

TAMFWIW, I'm not certain that what CTers are calling "Free Fall" speed refers to the velocity of the falling structural elements, I think what they are refering to as "Free Fall" speed is what they believe to be the elapsed time of collapse. In other words: "the buildings collapsed in less than 10 seconds, that means the buildings were collapsing at "Free Fall".

[T.A.M.]

SO perhaps a better term, one we should introduce to them, would be:

Free Fall Time

or

Time of Free Fall

TAM

[Metullus]

Yup. 'Cause they really need some new terms to bandy about.

[Belz...]

My apologies Dark Lord...but you are right

PWNED!! Mouahahahah!!...

... wait a minute! I'm not a CTer!! Woah! Sorry. Got carried away, there!

[Christophera]

It's a bundle of core columns. The same section that christophera continually mislabels are 'interior box columns'.

Mancman I think you've actually found the only image that might be legitimately labeled core columns, ... but they are not.

The first one that topples out has floor beams connecting 2 interior box columns. The few that stand momentarily cannot be seen clear enough to see the floor beams connecting them and might qualify, but because the stills which are clearer do not show columns in the core at many other phases, we can safely stay with the fact that no steel core columns are visible and the concrete core (http://algoxy.com/psych/images/southcorestands.gif) is.

Congratulations! Seriously, you have some real integrity when it comes to digging up evidence. Good try.

[Arus808]

I dont know what Christophera is smoking or is on, but several documentaries, including several that aired on A&E and Discovery, have all shown blueprints and mockups of the two Towers. And those documentaries, have stressed repeatedly that there were no concrete cores, because for a buildings of their sizes, the load weight, strain and stress would be too great for a them to do so. They went as so far to explain why and showed how the buildings collapse. Inside the Twin Towers was one such show.

[Stellafane]

...Congratulations! Seriously, you have some real integrity when it comes to digging up evidence. Good try.

Chris, you actually sit there -- a proven liar -- and question someone else's integrity? Sorry, liars such as yourself simply don't possess the moral authority.

Since you are a documented liar -- proven so by your own words -- nothing you say means anything to anyone.

[Kent1]

It's a bundle of core columns. The same section that christophera continually mislabels are 'interior box columns'.

Here's a better video of that same shot
http://www.911eyewitness.com/truth/downloads/spirefinish.wmv
And this one's good also
http://www.terrorize.dk/911/wtc1dem7/911.wtc.1.demolition.north.03.avi

[T.A.M.]

So I am confused now. Kent1 video shows collapse of the North Tower, but the last pciture Christophera just posted showing his "concrete" core is from the South Tower.

though from the 2nd video I can dfinitely conclude that there is no evidence of a "concrete" core in the North Tower.

TAM

[Brainache]

The first one that topples out has floor beams connecting 2 interior box columns. The few that stand momentarily cannot be seen clear enough to see the floor beams connecting them and might qualify, but because the stills which are clearer do not show columns in the core at many other phases, we can safely stay with the fact that no steel core columns are visible and the concrete

.

I promised myself not to do this, but Chris are you saying that steel core collumns shouldn't have floor beams connected to them?

I'm no structural engineer, but isn't that what a steel core does? Isn't it supposed to support all the floors?
Or is it a single 1300 ft piece of steel that only supports the roof?

[Hellbound]

I don't have the science to state categorically that a steel girder wouldn't reach terninal velocity during a 400m fall. I'd seriously doubt it though, as people skydiving take a much greater fall than that to reach termnal velocity, and steel girders are much bigger and denser than people.

Actually, they do.

Check this website (http://hypertextbook.com/facts/JianHuang.shtml) that gives some info on terminal velocities of skydivers. Most estimates about 53-56 m/s. At acceleration of gravity (9.8m/s2) they'll hit this speed in 5.4 to 5.7 seconds, and fall a total of 140m to 156m (d=v0t+1/2at2).

Without the science, you might as well be making stuff up. Well, actually, you are. "I don't think" is not scientific evidence, and is not admissible in a court of law, and frankly is not even enough to get a warrant to start an investigation. It's just the ramblings of one malcontent...without merit or meaning.

If you were actually interested in truth, you'd have taken the time to get the first-page results from two quick google searches on "human terminal velocity" and "acceleration equations"...but I suppose 5 minutes and a bit of multiplication is more than truth is worth?

Just for the sake of completeness, a steel girder would take 9.03 seconds to fall 400m, reaching a top speed of 88.5m/s (about 198 mph).

[Kent1]

So I am confused now. Kent1 video shows collapse of the North Tower, but the last pciture Christophera just posted showing his "concrete" core is from the South Tower.

though from the 2nd video I can dfinitely conclude that there is no evidence of a "concrete" core in the North Tower.

TAM
You might like these also
http://video.google.com/videoplay?docid=-1615521411849861778
http://www.terrorize.dk/911/wtc2dem1/

[mortimer]

Chris, there is no doubt in the latest videos that these are steel core columns. Much better evidence than your smoke cloud. Sorry, game over. There is NO evidence of a concrete core in this last video. NONE.

[einsteen]

If you consider the south tower (the one without antenna) then a block that turns a little bit and triggers a kind of process is quite interesting. The block will follow a simple parabolic track. It is of course in high contrast with "the merging of floors continuing their downward path"

The block itself also collapsed, because otherwise it should stay intact until it reaches the ground somewhere. It is impossible to collapse in the air because there is no initial 'helping hand' to let that block (that follows its own "free fall" part in the air) collapse, because it's assumed that the whole magical collapse process starts if the block collapses on the floor below. Why would the block also atomize into dust ? the magical process is a progressive collapse from top to down, under the damaged zone. Does the magical process flow back into the falling block ? That must be a smart process. The same argument for the other building.

[Kent1]

You might like these also
http://video.google.com/videoplay?docid=-1615521411849861778
http://www.terrorize.dk/911/wtc2dem1/
Here's another shot right before smoke flows in front of the spire as it falls.
http://www.terrorize.dk/911/wtc1dem6/911.wtc.1.spire.close.up.avi

[Brainache]

The block itself also collapsed, because otherwise it should stay intact until it reaches the ground somewhere. It is impossible to collapse in the air because there is no initial 'helping hand' to let that block (that follows its own "free fall" part in the air) collapse, because it's assumed that the whole magical collapse process starts if the block collapses on the floor below. Why would the block also atomize into dust ? the magical process is a progressive collapse from top to down, under the damaged zone. Does the magical process flow back into the falling block ? That must be a smart process. The same argument for the other building.



I'm sure you will get a more thorough debunking of this statement below, but I would point out to you that "the block at the top" is not a solid chunk like a piece of wood. It is some ten or twenty stories of a building designed to have vertical support.
I see it tipping slightly to one side and the downward pull of gravity(for lack of better words) acting on the structural members in a way that they weren't designed to withstand.

Do you seriously expect to see it tip to the side and drop to the ground like the top of a pole in a wood-chopping contest?

[einsteen]

Do you seriously expect to see it tip to the side and drop to the ground like the top of a pole in a wood-chopping contest?

The block is assumed to be heavy enough to break the damaged zone and start the initial process. I've seen photos of buildings that just came down untouched because of earthquickes etc but it's 5am now for me, time for bed.

[Gravy]

If you consider the south tower (the one without antenna) then a block that turns a little bit and triggers a kind of process is quite interesting. The block will follow a simple parabolic track. It is of course in high contrast with "the merging of floors continuing their downward path"

The block itself also collapsed, because otherwise it should stay intact until it reaches the ground somewhere. It is impossible to collapse in the air because there is no initial 'helping hand' to let that block (that follows its own "free fall" part in the air) collapse, because it's assumed that the whole magical collapse process starts if the block collapses on the floor below. Why would the block also atomize into dust ? the magical process is a progressive collapse from top to down, under the damaged zone. Does the magical process flow back into the falling block ? That must be a smart process. The same argument for the other building.
No neeed to get all anthropomorphic about it. Watch a close-up video of either collapse. The instant the tops start to tilt, they are also falling straight down through the structure below. The strong outer walls of the lower section no doubt helped keep things quite vertical. As Brainache points out, these are not solid structures pivoting on a steady fulcrum. They are disintegrating, crushing masses that gravity is trying to pull into the earth's core. As for the concrete buildings you've seen toppled by earthquakes, I suggest you take into account the differences in building construction, and the very different forces involved in the collapses.

[Blue Mountain]

(With reference to the declaration of Harold L Hill, Civil Engineer (http://forums.randi.org/attachment.php?attachmentid=2934&d=1157305577))

Gawd, Christophera has now been driven to create fake notes from engineers to support his fake documentary.

Why are you driven to lie about a tragedy in which 3,000 people died? Christophera, have you no shame? You shouldn't be abusing the memory of the dead in order to give meaning to your life. Please stop dishonoring the dead.

While I don't like defending Christophera, the basis of this board is not to draw conclustions until we have evidence. So, StoneWT, do you have any evidence Christopera faked this note?

I'll admit it's suspicious, but quite frankly it's also quite innocuous. He merely states he saw a documentary.

[LashL]

While I don't like defending Christophera, the basis of this board is not to draw conclustions until we have evidence. So, StoneWT, do you have any evidence Christopera faked this note?


I can't - and do not purport to - speak for StoneWT and I'm sure he or she is capable of speaking for himself/herself, but in the interim:

The note that Christophera provided, even if genuinely reproduced, is "fake" in the sense that Christophera purported that it was evidence of a(n) (structural? - not reading back through 3300 posts to find the exact words) engineer swearing that he, too, had seen the video that Christophera says he's seen which "proves" that the WTC towers had concrete cores rather than steel cores.

The note does not support Christophera's contentions at all, does not say that the signator saw the video that Christophera insists exists, does not even mention the concrete core that Christophera says existed, does not corroborate a single thing that Christophera purported that the note would corroborate.

That said, I wouldn't say that Christophera "faked the note" if that means manufactured it out of wholecloth, without further evidence to support that assertion, but I will certainly say that he has absolutely faked the relevance and content of it by virtue of his numerous misleading posts about it.

For the record, I also question the providence of the note, which is up to Christophera to prove. If it was legitimate, surely he would have been able to substantiate it. He has not done so.

[Pardalis]

If you consider the south tower (the one without antenna) then a block that turns a little bit and triggers a kind of process is quite interesting. The block will follow a simple parabolic track. It is of course in high contrast with "the merging of floors continuing their downward path"

The block itself also collapsed, because otherwise it should stay intact until it reaches the ground somewhere. It is impossible to collapse in the air because there is no initial 'helping hand' to let that block (that follows its own "free fall" part in the air) collapse, because it's assumed that the whole magical collapse process starts if the block collapses on the floor below. Why would the block also atomize into dust ? the magical process is a progressive collapse from top to down, under the damaged zone. Does the magical process flow back into the falling block ? That must be a smart process. The same argument for the other building.

Whoa! :eye-poppi

So what are you saying, the building didn't fall according to your understanding of how buildings fall?

Too bad

(see the first quote in my sig)

[mortimer]

Another reason the towers fell roughly into their own footprint is the steel outer shells of the towers. They would tend to push falling debris back towards the centers of the buildings before collapsing themselves.

[Metullus]

This discussion brings to mind my mis-spent youth. At one point in my tenure as a Boy Scout several of us had the bright idea that we could become overnight acrobats and entertain our fellow scouts at the evening campfire. Our goal: make a tower of boys four kids high (well 3 1/2 high really, the top kid was really small) with seven scouts (four on the bottom, and the others stacked above.)

Needless to say, we never succeded. We did get three high but the last guy kept collapsing us. The point is that when we fell we fell in a heap, even when the collapse was caused by the top guy over-balancing - in other words a top down collapse. We never toppled over like a tree, instead we collapsed in our own footprint, so to speak.

Kinda like the towers.

[Alareth]

This discussion brings to mind my mis-spent youth. At one point in my tenure as a Boy Scout several of us had the bright idea that we could become overnight acrobats and entertain our fellow scouts at the evening campfire. Our goal: make a tower of boys four kids high (well 3 1/2 high really, the top kid was really small) with seven scouts (four on the bottom, and the others stacked above.)

Needless to say, we never succeded. We did get three high but the last guy kept collapsing us. The point is that when we fell we fell in a heap, even when the collapse was caused by the top guy over-balancing - in other words a top down collapse. We never toppled over like a tree, instead we collapsed in our own footprint, so to speak.

Kinda like the towers.

Were your skeletons secretly wrapped in C4?

[Christophera]

Chris, you actually sit there -- a proven liar -- and question someone else's integrity? Sorry, liars such as yourself simply don't possess the moral authority.

Since you are a documented liar -- proven so by your own words -- nothing you say means anything to anyone.

The is no raw evidence for the steel core columns, A fact proven dozens of times right here in this very thread. I've not lied, you folks paint me as a liar when in fact you support lies.
The only core that can be evidenced with images of the demo is the concrete core (http://algoxy.com/psych/images/southcorestands.gif).

And the only explanaton for near free fall and total pulverization that exists on the web is based on the concrete core. Which is why it's so important to you folks that there was no concrete core.

http://algoxy.com/psych/9-11scenario.html

[Christophera]

I promised myself not to do this, but Chris are you saying that steel core collumns shouldn't have floor beams connected to them?

I'm no structural engineer, but isn't that what a steel core does? Isn't it supposed to support all the floors?
Or is it a single 1300 ft piece of steel that only supports the roof?

that is actually your problem to solve because there are no plans. The concrete core (http://algoxy.com/psych/images/southcorestands.gif) took 20% of the towers weight but primarily acted to resist lateral and torsional forces with its steel reinforced, rectangular cast concrete tubular shape.

To the left of the spire is the concrete shear wall. Notice no core columns left of it where they should be.

http://forums.randi.org/attachment.php?attachmentid=3003&stc=1&d=1157781276

[gumboot]

that is actually your problem to solve because there are no plans. The concrete core (http://algoxy.com/psych/images/southcorestands.gif) took 20% of the towers weight


So what held up the other 80% of the tower's weight? I would expect a concrete core to account for a great deal of the tower's weight. Maybe even more than 20%. Which would mean the core didn't even support it's own weight.

So what did? Pixie dust? Or was the rebar coating in magical nano-C4 that acts like an anti-gravity field?

-Andrew

[mortimer]

that is actually your problem to solve because there are no plans. The concrete core (http://algoxy.com/psych/images/southcorestands.gif) took 20% of the towers weight but primarily acted to resist lateral and torsional forces with its steel reinforced, rectangular cast concrete tubular shape.

To the left of the spire is the concrete shear wall. Notice no core columns left of it where they should be.

http://forums.randi.org/attachment.php?attachmentid=3003&stc=1&d=1157781276


Please make an arrow that points to the concrete shear wall in this photo. Sorry, Christopher, there's nothing in that photo but the "spire", dust, and other buildings.

[Dog Town]

near free fall

Your def please!

[Alareth]

SO perhaps a better term, one we should introduce to them, would be:

Free Fall Time

or

Time of Free Fall

TAM

Another term I have seen a few places (Including Abby's film) that shows utter ignorance is "speed of gravity"

Gravity is a constant that affects all objects. The amount of effect varys in relation to mass.

It does not have a speed.

[Brainache]

that is actually your problem to solve because there are no plans. The concrete core (http://algoxy.com/psych/images/southcorestands.gif) took 20% of the towers weight but primarily acted to resist lateral and torsional forces with its steel reinforced, rectangular cast concrete tubular shape.

To the left of the spire is the concrete shear wall. Notice no core columns left of it where they should be.

http://forums.randi.org/attachment.php?attachmentid=3003&stc=1&d=1157781276

So once again we have the problem of deciding if this image shows 3' rebar or a concete core, or as has been shown in high resolution close up the steel core collumns. I wish I could have avoided the urge to re-engage you on this Chris. The steel core has been shown many times. Not once has any evidence whatsoever for a concrete core been produced.
What kind of person are you who insist that things which are non existent must be there?
Is this just some kind of sick joke?
It isn't very funny.
I really do think you should be taking some kind of treatment for your condition.

[William Rea]

Another term I have seen a few places (Including Abby's film) that shows utter ignorance is "speed of gravity"

Gravity is a constant that affects all objects. The amount of effect varys in relation to mass.

It does not have a speed.

The mathematics is amazingly simple. There are two interesting ways of looking at the problem either in terms of forces and/or in terms of energy.

F (Force or what we consider weight) = m (mass) X a (acceleration)

For gravity we usually substitute g (gravitational force 9.81m/s^2)

Although g is constant, the velocity isn't. Initially the velocity of the upper floors would be zero and the forces acting upon the floors would be in equilibrium so that it is stationary. When that equilibrium of forces is upset say by catastrophic weakening of the structure the falling floors will accelerate by g and fall at increasing velocity until they reach either terminal velocity or another counter force acts upon them.

Terminal velocity is when forces opposing the fall (call them R) are in equilibrium with g and no further acceleration is possible although the falling floors are still moving they are not accelerating...

ma - R = 0 (velocity is constant)

A lot of people struggle here because as Newton observed, a body can be in equilibrium of forces but still be moving.

We must consider then what are the forces opposing g, my list of factors would be the following although I am sure anyone could add to the list...

1. Wind resistance.
2. falling into floors below (energy dissipation)
3. Distortion of steel framework (energy dissipation)

In energy terms the model is...

Total Energy = Potential Energy + Kinetic Energy + Losses

MgH = mgh + 0.5mv^2 + Losses

Interestingly, this explosive force accompanying the initial falling of the floors does not exist as such since the release of kinetic energy is not explosive.

In the above it is the losses that are key. What resistance existed? Bear in mind that energy lost to the Losses during the fall will reduce the kinetic energy and so the velocity of the falling floors.

I don't know how the towers fell anymore than the investigators seemed to in their report but I am suspicious of their claims.

[Oliver]

Just find any photo of the collapse in progress and ask them why the debris is falling faster than the building itself...and if the debris is falling faster than freefall. They dont like that argument, but they havent been able to counter it yet.

Delicious. :D

[William Rea]

Having read about the construction it is my understanding that the core is designed to hold the building up against direct gravity (in compression) and that the envelope of supports that double as the outer wall give the building a moment to resist toppling (compression and tension). the outer walls act as classical buttresses to support the core but the core bears the gravitational forces exerted by itself and the trussed floors.

Regardless of the construction of the core (remember concrete is very good in compression and steel reinforcement is only there to resist tension) I am surprised at the mode of failure for the towers. My expectation would be that the floors would certainly pancake on each other leaving the core remarkably intact and that the top would topple over the core and fall to the side of the building.

[GlennB]

Actually, they do.

...

Just for the sake of completeness, a steel girder would take 9.03 seconds to fall 400m, reaching a top speed of 88.5m/s (about 198 mph).

Criticism of shoddy argument accepted. Will try harder

So the girders and other dense, substantial debris do reach terminal velocity during a 400m fall? The equations in Wikipedia are way beyond my maths. Any volunteers?

[R.Mackey]

The block itself also collapsed, because otherwise it should stay intact until it reaches the ground somewhere. It is impossible to collapse in the air because there is no initial 'helping hand' to let that block (that follows its own "free fall" part in the air) collapse, because it's assumed that the whole magical collapse process starts if the block collapses on the floor below. Why would the block also atomize into dust ? the magical process is a progressive collapse from top to down, under the damaged zone. Does the magical process flow back into the falling block ? That must be a smart process. The same argument for the other building.
Sorry, this is just plain wrong, obviously wrong. As the block hits lower floors, Newton's Third Law applies, and both block and lower floors deform. The block hits over 60 floors on the way down, each one damaging the block almost as much as the floors below. There's nothing but rubble by the time the collapse stops.

[R.Mackey]

Criticism of shoddy argument accepted. Will try harder

So the girders and other dense, substantial debris do reach terminal velocity during a 400m fall? The equations in Wikipedia are way beyond my maths. Any volunteers?
This problem is a lot harder than it sounds, especially for steel girders, because their terminal velocity will be a strong function of whether the girder is falling down vertically (like a spear) or sideways. Much like people jumping out of planes reach about 120 MPH in proper position, but more like 180 MPH if head-down and arms tucked back.

The majority of debris hit other parts of the building on the way down, and very little of it started at roof height. The average starting height of material is more like half the building's height, or only 200m. I suspect few of the large chunks reached their drag-limited speed. Not sure it matters, either.

[gumboot]

Having read about the construction it is my understanding that the core is designed to hold the building up against direct gravity (in compression) and that the envelope of supports that double as the outer wall give the building a moment to resist toppling (compression and tension). the outer walls act as classical buttresses to support the core but the core bears the gravitational forces exerted by itself and the trussed floors.


I gather the exterior columns of the building actually carried a significant portion of the weight, as did the core. The floor trusses provided rigidity between the two "tubes".



Regardless of the construction of the core (remember concrete is very good in compression and steel reinforcement is only there to resist tension) I am surprised at the mode of failure for the towers. My expectation would be that the floors would certainly pancake on each other leaving the core remarkably intact and that the top would topple over the core and fall to the side of the building.

You mean like a tree?

Do you think the Keebler Elves would survive such an event?

By the way, a 60-storey or so section of the North Tower core remained standing a good 15-25 seconds after the rest of the building had collapsed.

-Andrew

[William Rea]

I gather the exterior columns of the building actually carried a significant portion of the weight, as did the core. The floor trusses provided rigidity between the two "tubes".

You mean like a tree?

Do you think the Keebler Elves would survive such an event?

By the way, a 60-storey or so section of the North Tower core remained standing a good 15-25 seconds after the rest of the building had collapsed.

-Andrew

I like your simplification of the structure into two tubes it is a good analogy except that the inner tube is built with immense strength very much like a tree trunk supporting branches. My understanding is that the inner tube carried the majority of the weight, even the weight transferred through the trusses from the concrete floors. The outer tube although significant is really a buttress transferring transverse forces from the inner core into the ground.

It is interesting that the inner core stood 15 to 25 seconds longer, it kind of bears out what I thought.

I tend not to read the conspiracy theory sites so I was not aware of the Keebler Elves story until now, now you have made me go and look I'm going to get dragged into it!

The tree is not a good analogy in terms of structural soundness and response to external forces. Wood is a very different material to steel and concrete so I don't accept the analogy in those terms except to point out that if you look at the remains of forest fires the cores or trunks often remain intact to the point that they are still able to resist considerable transverse forces and they are able to support their own weight.

[gumboot]

The tree is not a good analogy in terms of structural soundness and response to external forces. Wood is a very different material to steel and concrete


I'm glad we agree. The 9/11 "scholar" Judy Woods used the analogy of the top of a tree falling to claim the top section of the towers would have "tipped over" rather than compressing the remainder of the building.

Of course, trees are entirely solid, with a fairly high density, thus the amount of force needed to compress a tree trunk would be absolutely enormous.

In contrast, a building is primarily air, and as such has a very low density. The amount of force required to tip it over would be enormous - I have heard it would have to tip over its centre of gravity by several hundred feet in order to topple.

I recall, from the first time I saw the collapses, I described them as "peeling open like a banana" (I have always been mystified by the "looks like a CD" claim). Additional research confirms my interpretation - the forces of collapse pancaked the floors. As they gave way the building lost rigidity (because the floor trusses made the building rigid) thus, as the upper mass crashed down on the building the exterior cladding peeled outwards like a banana skin. This left the naked, stripped core, some of which remained standing for some time before it too collapsed (since I think we can agree the core of the WTC, having suffered the collapse of the rest of the structure, was not going to remain standing).

-Andrew

[Belz...]

Mancman I think you've actually found the only image that might be legitimately labeled core columns, ... but they are not.

???

The first one that topples out has floor beams connecting 2 interior box columns. The few that stand momentarily cannot be seen clear enough to see the floor beams connecting them and might qualify, but because the stills which are clearer do not show columns in the core at many other phases, we can safely stay with the fact that no steel core columns are visible and the concrete core (http://algoxy.com/psych/images/southcorestands.gif) is.

Only problem is, if the concrete core WAS there you'd see it in the video. All you see is those columns. Where's the concrete in the video, Chris ?

Congratulations! Seriously, you have some real integrity when it comes to digging up evidence. Good try.

So integrity is finding videos and images that can agree with ?

[Belz...]

The block itself also collapsed, because otherwise it should stay intact until it reaches the ground somewhere. It is impossible to collapse in the air because there is no initial 'helping hand' to let that block (that follows its own "free fall" part in the air) collapse, because it's assumed that the whole magical collapse process starts if the block collapses on the floor below. Why would the block also atomize into dust ?

Atomise ? You need to check those pictures of ground zero again.

the magical process is a progressive collapse from top to down, under the damaged zone. Does the magical process flow back into the falling block ? That must be a smart process. The same argument for the other building.

Are you saying that the top section, coming down in the relatively intact bottom section, shouldn't have been demolished as it fell down ?

[einsteen]

Well, whether it topples of not, it is assumed to start the magical process, it is assumed that the total mass of the block at top containing n floors will 'merge' with the floor below and that this (n+1) store floor will repeat the process but then with a new speed. It is obvious from the movies that once things pulverize it does not merge as a new block, small particles like dust will reach their maximal speed very quickly, a lot of mass is 'hanging' in the air as you an see, ok but alright then, if you assume this you get a theoretical bottom value, for a total elastic (billiard balls) situation the collapse you get a theoretial upper value, the real value then must be between this, of course the situation becomes extremely complex and an exact calculation is not trivial.

This site got some detailed pitures

http://thewebfairy.com/nerdcities/WTC/south-tower.htm

[Belz...]

I don't know how the towers fell anymore than the investigators seemed to in their report but I am suspicious of their claims.

Why ?

Regardless of the construction of the core (remember concrete is very good in compression and steel reinforcement is only there to resist tension) I am surprised at the mode of failure for the towers. My expectation would be that the floors would certainly pancake on each other leaving the core remarkably intact and that the top would topple over the core and fall to the side of the building.

Like in cartoons...

[Belz...]

Well, whether it topples of not, it is assumed to start the magical process,

What "magical" process are you refering to ? This kind of attitude doesn't reinforce the notion that you're here to debate and learn.

it is assumed that the total mass of the block at top containing n floors will 'merge' with the floor below and that this (n+1) store floor will repeat the process but then with a new speed. It is obvious from the movies that once things pulverize it does not merge as a new block, small particles like dust will reach their maximal speed very quickly, a lot of mass is 'hanging' in the air as you an see, ok but alright then, if you assume this you get a theoretical bottom value, for a total elastic (billiard balls) situation the collapse you get a theoretial upper value, the real value then must be between this, of course the situation becomes extremely complex and an exact calculation is not trivial.

What's your point, here ?

[einsteen]

My point is that F.R.Greenings theoretical bottom value is under the assumption of a block that grows each floor. If we have N floors and the initial block that falls contains n floors, then the next one contains (n+1) floors and so on, at the bottom the first floor will then finally crash because

((n+1)+1)+...+1)=N-1 floors will fall on it, this in fact is assumed to be a solid block (in fact the whole building) transferring it's momentum and energy. It's obvious from the videos that this is not the case, there is no doubt about it that that is the thing that happens, no chance at all, nothing.

Well, if you expect the initial block falls into pieces, then you really cannot assume this. Even the block I assumed is believed to be falling in pieces, but F.R. Greening assumes the block will only grow, floor by floor.

[Brainache]

Sorry Einsteen. I don't quite follow your banter old man.
What does that mean?
Are you saying that the top should have remained all in one piece all the way down?

[rwguinn]

My point is that F.R.Greenings theoretical bottom value is under the assumption of a block that grows each floor. If we have N floors and the initial block that falls contains n floors, then the next one contains (n+1) floors and so on, at the bottom the first floor will then finally crash because

((n+1)+1)+...+1)=N-1 floors will fall on it, this in fact is assumed to be a solid block (in fact the whole building) transferring it's momentum and energy. It's obvious from the videos that this is not the case, there is no doubt about it that that is the thing that happens, no chance at all, nothing.

Well, if you expect the initial block falls into pieces, then you really cannot assume this. Even the block I assumed is believed to be falling in pieces, but F.R. Greening assumes the block will only grow, floor by floor.

ok, here's how it works.
go out and find yourself a dirt clod.
Weigh it.
throw it against the ground.
weigh al the pieces and dust.
amazing! they weigh the same!
Matter can neither be created nor destroyed, merely transformed.
when the top flooors start falling, they break up. the vast majority of the pieces add themselves to the mass hitting the floor below, which also breaks up and falls. most of that hits the next floor.
Even though it is in pieces, it still has mass, and given that it is moving, it has momentum and energy.
There is some loss, because dust particles will hit terminal velocity rather quickly, but even though there is a tremendous amount of dust, the vast majority of the stuff is of pebble-size and larger (much larger!).
Have someone empty a bucket of gravel or sand on your head from your roof. After you get back from the hospital, contemplate the reality of Newtonian physics.

[Hellbound]

Criticism of shoddy argument accepted. Will try harder

So the girders and other dense, substantial debris do reach terminal velocity during a 400m fall? The equations in Wikipedia are way beyond my maths. Any volunteers?

The girders I don't know, I was speaking of the skydivers. Sorry if I didn't make that clear. I doubt a plain girder, falling vertically, would reach terminal velocity. However, this one is going to depend on the orientation ,surface area presented to the direction of motion, and lots of calculus, which is beyond my abilities (and therefore I make no claims on that part). gravity acceleration alone, however, provides a 9 second fall time (for 400m) and a top speed of ~200mph.

I'm not really seeing that it makes that much difference, though, whether or not they hit terminal velocity.

[Christophera]

Sorry Einsteen. I don't quite follow your banter old man.
What does that mean?
Are you saying that the top should have remained all in one piece all the way down?

No wonder folk here think there was a collapse in NYC on 9-11.

Einsteen says that Greening thinks that it should have remained in one piece all the way down.

Because of the appearance of the image at bottom, and fact that the official story does not explain its being pulverized BEFORE it hits the ground, the only explanation is found here,

http://algoxy.com/psych/9-11scenario.html

I much prefer getting hit on the head with a bucket of sand than a bucket of gravel or the worst case, a bucket of yesterdays concrete, hardened, and, there is a reason for this that has been completely ignored,


http://forums.randi.org/attachment.php?attachmentid=3006&stc=1&d=1157818503

[Pardalis]

My point is that F.R.Greenings theoretical bottom value is under the assumption of a block that grows each floor. If we have N floors and the initial block that falls contains n floors, then the next one contains (n+1) floors and so on, at the bottom the first floor will then finally crash because

((n+1)+1)+...+1)=N-1 floors will fall on it, this in fact is assumed to be a solid block (in fact the whole building) transferring it's momentum and energy. It's obvious from the videos that this is not the case, there is no doubt about it that that is the thing that happens, no chance at all, nothing.

Well, if you expect the initial block falls into pieces, then you really cannot assume this. Even the block I assumed is believed to be falling in pieces, but F.R. Greening assumes the block will only grow, floor by floor.
emphasis mine

Grow?

What in the freaking hell (sorry Belz) are you talking about?

What is this stupid pseudo science? What do you do for a living again?

[R.Mackey]

No wonder folk here think there was a collapse in NYC on 9-11.

Einsteen says that Greening thinks that it should have remained in one piece all the way down.
Einsteen is wrong. Greening says nothing of the kind.

You might try reading Greening's paper (http://www.911myths.com/WTCREPORT.pdf) for yourself, rather than relying on somebody else's off-the-cuff, completely misleading analysis, if you had any interest whatsoever in research.

Because of the appearance of the image at bottom, and fact that the official story does not explain its being pulverized BEFORE it hits the ground, the only explanation is found here,

[Link to unproven, fantastical, lunatic delusions deleted]
Your "fact" is a lie. The official story explains the mechanics of collapse thoroughly.

I much prefer getting hit on the head with a bucket of sand than a bucket of gravel or the worst case, a bucket of yesterdays concrete, hardened, and, there is a reason for this that has been completely ignored,
Ignored by whom?

The reason is a distinction between momentum and energy. A truckload of sand dumped on you from a few stories will kill you quite effectively. Greening treats both in his paper. The subject is not ignored, and you have lied again. Except I'll let you off easy because I strongly suspect you lack the education to appreciate the difference. But please, go try to learn something about basic physics. If you refuse to learn from people here, you're just going to have try something else.

[Regnad Kcin]

Mr. Brown:

I see you are posting your "thoughts"* over at the Loose Change forum. Do you honestly think that contributing to one Internet forum after another is going achieve anything?

So I ask you again: What are your plans for providing your evidence, such as it is, to one or more scientific journals?

Oh, by the way...

You folks are aiding and abetting murderers...Name them.

*That is, misinformation and lies.

[Regnad Kcin]

...I'll address your towers-fell-in-the-wrong-order inaccuracy. I suspect it'll be for naught, but what the hey.

First, I was attempting to walk you through the simple deductive process when I initially engaged you on the matter. But your general unresponsiveness proved continually taxing. Then, when you returned after your suspension (not "ban," as you lied on the physorg forum), you continued your difficult manner.

But let's get to it.

The 110-story WTC 1 was struck first by a Boeing 767 at approx. 490 mph. The floors damaged were between 93 and 99. This left 11 undamaged stories above. The tower fell 102 minutes after impact.

The 110-story WTC 2 was subsequently struck by a Boeing 767 at approx. 590 mph. The floors damaged were between 77 and 85. This left 25 undamaged stories above. The tower fell 56 minutes after impact.

Please don't tell me I have to explain this any further.Mr. B:

Your silence, in regard to the above, is deafening.

Oh, and what was the name of your imaginary BBC/PBS documentary, again?

[Christophera]

Einsteen is wrong. Greening says nothing of the kind.

You might try reading Greening's paper (http://www.911myths.com/WTCREPORT.pdf) for yourself, rather than relying on somebody else's off-the-cuff, completely misleading analysis, if you had any interest whatsoever in research.


You might try reading what I wrote, if you had any interest in quality communication.

[Christophera]

Mr. Brown:

I see you are posting your "thoughts"* over at the Loose Change forum. Do you honestly think that contributing to one Internet forum after another is going achieve anything?

So I ask you again: What are your plans for providing your evidence, such as it is, to one or more scientific journals?

Oh, by the way...

Name them.

*That is, misinformation and lies.

Dear Mr. Peabody.

I know there have been murders and I know that you are defending their lies, this does not mean I know who they are.

Science BTW, since 9-11, has suffered great credibility loss.

[R.Mackey]

You might try reading what I wrote, if you had any interest in quality communication.
As if it needed further proof, this pathetic attempt at rebuttal demonstrates that you have no inclination, and perhaps no ability, to provide such.

I can't believe you thought I'd be impressed by that.

[Regnad Kcin]

I know there have been murders and I know that you are defending their lies...Just like you "know" about the documentary that you can't find? Just like you "know" the towers fell in the wrong sequence? Just like you "know" there are 3" rebars of 4' centers? Just like you "know" some shadowy, unnamed group installed explosives when the WTC was constructed decades ago? Just like you "know" a single, still image of a smokey, rapidly changing, dynamically violent event reveals a concrete core -- the existence of which cannot be verified on any plans, drawings, or descriptions, vouched for by any architect or structural engineer, and which not one eyewitness will attest to existing?

...this does not mean I know who they are.A remarkable admission on your part. Congratulations. Now, why not try to build from there?

Science BTW, since 9-11, has suffered great credibility loss.You are perhaps the least qualified I know to judge anyone's credibility.

[einsteen]

Have someone empty a bucket of gravel or sand on your head from your roof. After you get back from the hospital, contemplate the reality of Newtonian physics.

:jaw-dropp I don't like this way of conversation. Why that aggresive, what did I do to you ? I know enough of Newtonian mechanics.

[Belz...]

My point is that F.R.Greenings theoretical bottom value is under the assumption of a block that grows each floor.

[...]

It's obvious from the videos that this is not the case, there is no doubt about it that that is the thing that happens, no chance at all, nothing.



It doesn't matter if floors above were pulverized or otherwise destroyed. A million tons of concrete and steel weighs a million tons no matter in what shape it is in.

[Belz...]

No wonder folk here think there was a collapse in NYC on 9-11.

Einsteen says that Greening thinks that it should have remained in one piece all the way down.

Because of the appearance of the image at bottom, and fact that the official story does not explain its being pulverized BEFORE it hits the ground, the only explanation is found here,

http://algoxy.com/psych/9-11scenario.html

Are you saying that explosives in the top portion of the towers went of AS THAT PORTION FELL TO THE GROUND ???

I much prefer getting hit on the head with a bucket of sand than a bucket of gravel or the worst case, a bucket of yesterdays concrete, hardened, and, there is a reason for this that has been completely ignored,

It doesn't matter. If it's the same weight, it's going to have pretty much the same effect. A ton's a ton.

[Belz...]

:jaw-dropp I don't like this way of conversation. Why that aggresive, what did I do to you ? I know enough of Newtonian mechanics.

Obviously not, since you seem to think that pieces of steel and cement weigh less once they are broken apart.

[einsteen]

Obviously not, since you seem to think that pieces of steel and cement weigh less once they are broken apart.

Of course not mate, thats not what I said. I should not use the word 'solid' block. A lot of mass is scattered in all directions, of course the conservation of mass can't be violated, but the part traveling down together with the upperblock is not

(n+1)m_floor (Greening)

but

(wn+1)m_floor,

with w the fraction of the mass traveling downwards. Greening didn't use that, also note that w is not constant, it will be a complicated function for which we only know 0< w<1

[T.A.M.]

Einsteen:

Your english has gotten much better, very quickly. You must be using some sort of software, or you must have gotten lessons. That last post didn't have one single error in it from an english language point of view, and you even used the "British/Aussie" slang "mate".

Good going. If I could learn language as easy, I would speak fluent Chinese.

:)

TAM

[einsteen]

Einsteen:

Your english has gotten much better, very quickly. You must be using some sort of software, or you must have gotten lessons. That last post didn't have one single error in it from an english language point of view, and you even used the "British/Aussie" slang "mate".

Good going. If I could learn language as easy, I would speak fluent Chinese.

:)

TAM

My physics teacher once said there is less English knowledge needed to understand a physics book than an average novel book. Ok, I take more time to formulate, I had a bad week also, but that's personal

[einsteen]

Again the word 'block' is wrong.

As fas as I understand Greening considers a block that falls, collects mass etc to the ground, he calls it the first stage of collapse. After the whole bunch reaches the ground he calculates a second stage of collapse, it is consistent with the seismic data, but as far as I understand he calculates this only for the block itself

[Pardalis]

Again the word 'block' is wrong.

And what about 'grow'?

[T.A.M.]

Einsteen:

much better for you to take your time then. Your last two posts have been entirely legible, which will go a long way in helping you express your points clearly here.

TAM

[Metullus]

Were your skeletons secretly wrapped in C4?Well, yeah, now that you mention it...

[einsteen]

I went to 75% of F.R. Greening's document WTCREPORT.pdf and have some serious questions. His excel sheets, values for floor, masses etc will surely be correct. We don't have to reinvent the wheel. I admit that I don't understand everything at the moment (it's been awhile), but if you debug a source code you also don't have to know it completely.

Upper block falls

This is assumed by TV coverage, it does not explain why this happened, ok but you have to start with something, allright then.

Uniform mass distribution

In reality that's not true, hence the final result will differ a little bit, but allright for a first approximation

Non-elastic collision

This is not what we see from the same TV coverage, as an object breaking floors below, all the dust and crushed concrete staying 'under' the block and traveling in the same direction. If you do a gedankenexperiment in which you assume this then it's ok, but for a first approximation of the theoretical minimum collapse time you already should take other factors into account, the time could be extremely dependent on these factors or maybe not.

Tacitly assumed that the impulsive delivered by the impact is sufficient to rupture...

Why?

The second stage of collapse

Absolutely relevant for the seismic data, but not really relevant for the speed at which the buildings come down.

For now it is sufficient to note that the collapse times calculated without allowing for E1 are already in reasonable agreement with the observed collapse times.

Of course because this is the theoretical minimum time and that should be near free-fall time because in fact section 3.0 of the paper assumes no resistance in any way, in fact point masses with non-elastic collapses merging into each other without any of the mass moving at an other directory

However, to more precisely model the physics of the WTC collapse events, we need to consider the bending and fracturing energy, E1, that must be expended to collapse each floor

Great but this is still under the assumption of all mass falling down in the same direction to break the next floor.

But the initial kinetic energy Ti is equal to (1/2)Nm_f u^2 so the fractional conversion, fc, of kinetic energy to heat is simply,
fc = Q/Ti = 1/(1 + N)

This is an amazing result IMO, but indeed under the assumption no mass is scattered away from floor N to floor N-1 to ... to floor 1

If we assume 50 % of this energy was available to crush concrete, we have 1.2 x 10^9 J available for WTC 1, and 2.5 x 10^9 J available for WTC 2. This is sufficient to crush the concrete on the impacted floor to 175 micrometer particles. Consider now the newly formed mass of (14 + 1) floors of WTC 1, and (29 + 1) floors of WTC 2, impacting on the floor below.

An amazing amount of energy indeed. Again all crushed concrete is assumed to form a new mass to crush the next floor. Check some videos and detailed pictures, it's absolutely impossible to consider this as a first approximation, the mass scatters in all directions, even upwards. Of course the conservation of mass can't be violated, but the part traveling down together with the initial upperblock is not

(n+1)m_floor

but should be

n m_floor +w m_floor =(n+w)m_floor (**** I wrote it wrong at top)

with w the fraction of the mass traveling downwards. Greening didn't use that, also note that w is not constant, it will be a complicated function (dependent on some variables) for which we only know 0< w<1, it should be estimated.

Further small particles are very sensitive to air resistance and the rest of the crap in the air and the so-called terminal speed is reached very quickly, I'm not sure if the factor w can take that into acount or if another factor is needed for that somewhere. Maybe I'm wrong also now and all these factors seem to have not much influence on the theoretical minimum, but it was just something I thought after reading a little bit.


But now it's time to go out and have some beers, my wife is a little bit angry.. "you should marry with your computer" etc..

[Belz...]

Of course not mate, thats not what I said. I should not use the word 'solid' block. A lot of mass is scattered in all directions, of course the conservation of mass can't be violated, but the part traveling down together with the upperblock is not

(n+1)m_floor (Greening)

but

(wn+1)m_floor,

with w the fraction of the mass traveling downwards. Greening didn't use that, also note that w is not constant, it will be a complicated function for which we only know 0< w<1

The point is, most of the mass will come down on the lower floors. It doesn't matter if it's dust or solid steel. It comes down on the floor and the floor can't handle it. Ergo, it fails.

[R.Mackey]

Einsteen, I'm glad you're thinking about this, and I applaud you for struggling through language difficulties, but you're just not thinking about it clearly. Let me try to help.

Upper block falls

This is assumed by TV coverage, it does not explain why this happened, ok but you have to start with something, allright then.
Where else would the block go? I'm confused. Gravity will pull it downward.

Non-elastic collision

This is not what we see from the same TV coverage, as an object breaking floors below, all the dust and crushed concrete staying 'under' the block and traveling in the same direction. If you do a gedankenexperiment in which you assume this then it's ok, but for a first approximation of the theoretical minimum collapse time you already should take other factors into account, the time could be extremely dependent on these factors or maybe not.
No, einsteen, you're wrong. The collision is inelastic. The collision can only be elastic, the alternative, if no energy is dissipated in breaking or bending things when they hit. This is impossible. Greening's asumption is correct. His mathematics allow for fragmentation.


Tacitly assumed that the impulsive delivered by the impact is sufficient to rupture...

Why?
Because in this part of the paper he's considering timing. He addresses the energy required for progressive collapse elsewhere. Thoroughly.

[The second stage of collapse

Absolutely relevant for the seismic data, but not really relevant for the speed at which the buildings come down.
The timing information is derived from seismic data. It's relevant to both.

For now it is sufficient to note that the collapse times calculated without allowing for E1 are already in reasonable agreement with the observed collapse times.

Of course because this is the theoretical minimum time and that should be near free-fall time because in fact section 3.0 of the paper assumes no resistance in any way, in fact point masses with non-elastic collapses merging into each other without any of the mass moving at an other directory
Wrong. The paper assumes resistance from structure and inertia of lower floors. It does not take wind resistance into account -- which is correct. The floors are not falling into a free-stream of air, they're falling into structure, and the structure's resistance is accounted for.

But the initial kinetic energy Ti is equal to (1/2)Nm_f u^2 so the fractional conversion, fc, of kinetic energy to heat is simply,
fc = Q/Ti = 1/(1 + N)

This is an amazing result IMO, but indeed under the assumption no mass is scattered away from floor N to floor N-1 to ... to floor 1
If you notice, the energy budget is far higher than needed. You will see a little bit of mass shed off the sides, but not much. Inelastic, remember? Stuff doesn't bounce off at full speed. You only lose a little mass on the edges, or the unlucky piece of steel that breaks and throws fragments.

You could easily estimate how much fell off the sides by comparing the distribution of debris after the collapse was over. Nearly all of it was in one central pile. The losses were small, perhaps 10% in mass.


If we assume 50 % of this energy was available to crush concrete, we have 1.2 x 10^9 J available for WTC 1, and 2.5 x 10^9 J available for WTC 2. This is sufficient to crush the concrete on the impacted floor to 175 micrometer particles. Consider now the newly formed mass of (14 + 1) floors of WTC 1, and (29 + 1) floors of WTC 2, impacting on the floor below.

An amazing amount of energy indeed. Again all crushed concrete is assumed to form a new mass to crush the next floor. Check some videos and detailed pictures, it's absolutely impossible to consider this as a first approximation, the mass scatters in all directions, even upwards. Of course the conservation of mass can't be violated, but the part traveling down together with the initial upperblock is not

(n+1)m_floor

but should be

(wn+1)m_floor,

with w the fraction of the mass traveling downwards. Greening didn't use that, also note that w is not constant, it will be a complicated function (dependent on some variables) for which we only know 0< w<1, it should be estimated.
The bulk of the tower's mass is not concrete, and is not crushable. Your fudge factor W will be close to 1.

Also remember that mass that "scatters" will only do so by impacting the lower structure very hard. It has already contributed most of the energy that a piece that stayed with the column would have. Your losses are just not high enough to invalidate his hypothesis.

Further small particles are very sensitive to air resistance and the rest of the crap in the air and the so-called terminal speed is reached very quickly, I'm not sure if the factor w can take that into acount or if another factor is needed for that somewhere. Maybe I'm wrong also now and all these factors seem to have not much influence on the theoretical minimum, but it was just something I thought after reading a little bit.
Again, only the stuff that falls off the sides is in a free-stream of air. And we've already discounted it. Fine pieces still in the core structure do not experience meaningful drag.

If you want to explore the effect of pieces falling off the sides, just re-run Greening's calculation but reduce the mass of each floor, say by 5%, 10%, on up to 100%. Find how the calculation behaves as a function of debris loss.

Then take a look at the collapse pile, estimate a debris loss fraction, and see where you wind up with his collapse equations.

Having done this, I believe you'll find that his equations are quite credible, especially considering they are a simplification.

[William Rea]

I'm glad we agree. The 9/11 "scholar" Judy Woods used the analogy of the top of a tree falling to claim the top section of the towers would have "tipped over" rather than compressing the remainder of the building.

Of course, trees are entirely solid, with a fairly high density, thus the amount of force needed to compress a tree trunk would be absolutely enormous.

In contrast, a building is primarily air, and as such has a very low density. The amount of force required to tip it over would be enormous - I have heard it would have to tip over its centre of gravity by several hundred feet in order to topple.

I recall, from the first time I saw the collapses, I described them as "peeling open like a banana" (I have always been mystified by the "looks like a CD" claim). Additional research confirms my interpretation - the forces of collapse pancaked the floors. As they gave way the building lost rigidity (because the floor trusses made the building rigid) thus, as the upper mass crashed down on the building the exterior cladding peeled outwards like a banana skin. This left the naked, stripped core, some of which remained standing for some time before it too collapsed (since I think we can agree the core of the WTC, having suffered the collapse of the rest of the structure, was not going to remain standing).

-Andrew

Actually we don't agree, you have inferred something from my posts that I did not say.

I have no idea who Judy Wood is but she is probably saying that if you saw the top of a tree off it topples off because the underlying support is sound. I would not argue with that since the damage to the towers would be akin to cutting them off at the top.

For a small section of the top of the tower to topple wouldn't actually take much if the impact damage changed the balance of forces significantly. It would be somewhat like trying to balance to top of a tree that has been sawn through with a wedge removed (as traditional woodsmen cut).

Additionally, your contrast isn't a contrast. All you have said is that dense materials resist compression well and lighter constructions built with high moments of area don't topple easily.

Water is denser than wood (that's why wood floats) but it wouldn't resist compression as well as a comparable thickness of tree. The structure of a tree is tough and strong because it has a fibrous nature, density is not the single factor that determines strength and toughness.

Light framework constructions are designed to transfer loads with safety factors so that they resist certain modes of failure be they buckling, bending or fracture. I think it would be odd for the designer of the building not to make a space frame that could resist the forces of its own weight several times over. To say that the steel space frame would be poor in compression because it is less dense than wood is absurd. I pointed this out in my previous post that the tree analogy is good in principle for the layman to understand how the building works but it is very limited.

[William Rea]

Why ?

Like in cartoons...

You are as irrelevant to me as your posts. I have no interest in corresponding with you.

[Z]

You are as irrelevant to me as your posts. I have no interest in corresponding with you.
Then put him on ignore. Or, better still, don't post in an open forum he's known to frequent.

[William Rea]

Then put him on ignore. Or, better still, don't post in an open forum he's known to frequent.

I didn't request your intervention either.

[kevin]

I didn't request your intervention either.

nor did we request yours.

[gumboot]

Actually we don't agree, you have inferred something from my posts that I did not say.

In this (http://forums.randi.org/showpost.php?p=1907882&postcount=3358)
post you said:

The tree is not a good analogy in terms of structural soundness and response to external forces. Wood is a very different material to steel and concrete

I agree with this assertation, thus we are in agreement on this point. Unless you wish to retract your statement?



I have no idea who Judy Wood is but she is probably saying that if you saw the top of a tree off it topples off because the underlying support is sound. I would not argue with that since the damage to the towers would be akin to cutting them off at the top.


Oh so you DO agree with her assertation?



For a small section of the top of the tower to topple wouldn't actually take much if the impact damage changed the balance of forces significantly.

"wouldn't actually take much"
"changed the balances of forces significantly"

See any problem with these two statements in the same sentence?




It would be somewhat like trying to balance to top of a tree that has been sawn through with a wedge removed (as traditional woodsmen cut).


Except a building is not a solid object, like a tree. It is a structure, comprised of many solid objects, and a whole heap of air.



Additionally, your contrast isn't a contrast. All you have said is that dense materials resist compression well and lighter constructions built with high moments of area don't topple easily.


You see no contrast between a tree - which is solid wood - and a building, which consists mainly of air?

Curious...




Light framework constructions are designed to transfer loads with safety factors so that they resist certain modes of failure be they buckling, bending or fracture. I think it would be odd for the designer of the building not to make a space frame that could resist the forces of its own weight several times over.


Do you know the difference between a static load and a live load?




To say that the steel space frame would be poor in compression because it is less dense than wood is absurd. I pointed this out in my previous post that the tree analogy is good in principle for the layman to understand how the building works but it is very limited.

I did not say that. I said the STRUCTURE would be poor in compression because it is mainly air.

If you rip a chunk out of a tree, the top falls on the bottom, which is a rigid solid block of wood directly connected to the ground. Essentially that upper portion is being resisted by the ground itself. Obviously the tree trunk isn't going to compress. As a result the top topples over (there's nowhere else for it to go).

In contrast, rip a chunk out of a building, and the top floors crash down on a structure of solid objects with a heap of air amongst it. The forces of impact greatly exceed the capacity of the structure, so it fails.

Or to put it another way, drop a rock on a tree, and the rock will bounce off the tree and fall away. Drop an enormous rock on a forest and you'll flatten the forest.

A building is not a tree. It is a "forest" of support pillars.

The video of the collapses clearly show the various individual "trees" (column sections) toppling over, just like a tree. But the STRUCTURE (the forest) collapses.

-Andrew

[T.A.M.]

William (or is it Paul, I can't remember)

What is the point of your rudeness? So he made an off handed remark, there is no need for you to be snotty and antagonist about it, especially since you have not been on these boards nearly as long as he.

Put us all on ignore if it will make you think clearer, or make you less angry.

TAM

[rwguinn]

Actually we don't agree, you have inferred something from my posts that I did not say.

I have no idea who Judy Wood is but she is probably saying that if you saw the top of a tree off it topples off because the underlying support is sound. I would not argue with that since the damage to the towers would be akin to cutting them off at the top.

For a small section of the top of the tower to topple wouldn't actually take much if the impact damage changed the balance of forces significantly. It would be somewhat like trying to balance to top of a tree that has been sawn through with a wedge removed (as traditional woodsmen cut).
bull stuff! A structure, whether it be tree or building, topples because the center of mass has been moved outside the footprint of its suppport. This is easy on a long, slender structure, such as a radio tower, or a tree.
For a part, or all, of the twin towers to topple, the CG would have to move more than 100 feet laterally, or 141 feet diagonally. The reason the upper part "toppled" was that the remaining supports had moved to one side of the building (one side failed)

Additionally, your contrast isn't a contrast. All you have said is that dense materials resist compression well and lighter constructions built with high moments of area don't topple easily.

Water is denser than wood (that's why wood floats) but it wouldn't resist compression as well as a comparable thickness of tree. The structure of a tree is tough and strong because it has a fibrous nature, density is not the single factor that determines strength and toughness. water resists compression better than most solids-in fact, if you fil a cylinder of steel with water, and try to compress it with a steel piston, you wiil fail the steel, either piston or cylinder

What, however, does al this have to do with thye CG being outside the base?


Light framework constructions are designed to transfer loads with safety factors so that they resist certain modes of failure be they buckling, bending or fracture. I think it would be odd for the designer of the building not to make a space frame that could resist the forces of its own weight several times over. To say that the steel space frame would be poor in compression because it is less dense than wood is absurd. I pointed this out in my previous post that the tree analogy is good in principle for the layman to understand how the building works but it is very limited. you will find that the failure mode of every steel part was either bending, or buckling (which is a fancy name for bending due to compressive instability)
That sort of thing happens when the designed " Light framework construction" is severly compromised.

[William Rea]

William (or is it Paul, I can't remember)

What is the point of your rudeness? So he made an off handed remark, there is no need for you to be snotty and antagonist about it, especially since you have not been on these boards nearly as long as he.

Put us all on ignore if it will make you think clearer, or make you less angry.

TAM

I was simply making it clear that his post was not welcome and he/she would not elicit a flamed response from me either now or in the future. Quite simple protocol which I didn't realise meant that I should be anything other than firm, would flowery language have made the offence I seem to have caused any less?

Seems like everyone is an amateur moderator on here just itching to intervene.

I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however, If the forum owner doesn't want me here expanding the membership of the forum and eliciting further posts I will happily leave. It seems that already I have generated some traffic from the hostile time servers on the forum.

[twinstead]

I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however, If the forum owner doesn't want me here expanding the membership of the forum and eliciting further posts I will happily leave. It seems that already I have generated some traffic from the hostile time servers on the forum.

A simple perusal of the other posts on this board should assuage your fears; the only way, other than of course breaking the forum rules, to loose respect on this forum is to repeatedly claim things without legitimate evidence.

[Arkan_Wolfshade]

I was simply making it clear that his post was not welcome and he/she would not elicit a flamed response from me either now or in the future. Quite simple protocol which I didn't realise meant that I should be anything other than firm, would flowery language have made the offence I seem to have caused any less?

Seems like everyone is an amateur moderator on here just itching to intervene.

I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however, If the forum owner doesn't want me here expanding the membership of the forum and eliciting further posts I will happily leave. It seems that already I have generated some traffic from the hostile time servers on the forum.

"I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however," and then you have the gall to complain when other people reply to your posts in a manner for which you don't care? :boggle: Anyone abiding by the stated rules is welcome here; viewpoints regardless. That said, don't expect to be welcomed by everyone in the same way because the open policy applies to all sides and all points of view.

[Kent1]

For those looking for the best shots of the spire during the collapse, I would recommend A&E Trapped in the Towers: The Elevators of 9/11.

[Christophera]

A testimonial from someone who had talked with a high ranking engineer at otis elevator who described "built to demolish towers", has been completely ignored by the posters of this thread.

http://www.rense.com/general48/chargesplacedinWTC.htm

Here is the site that explains how, what that engineer said was done, was actually done.

http://algoxy.com/psych/9-11scenario.html

[Alareth]

You know, at this point even a brick wall would have given up.

You really have to admire the sheer tenacity of sticking with such a laughable lost cause.

[Brainache]

Still not taking your medication I see. Please get help.

[Architect]

I have to hand it to Chris; sticking with C4 coated rebar (http://algoxy.com/psych/9-11scenario.html) when he can't actually prove that such a material exists. :covereyes

Here's my theory; they screwed up the order and got chocolate coated rebar instead; the heat of the fire caused melting and shear on the chocolate/concrete line and the towers failed.

No evidence? Hell, I got just as much as Chris has.......:)

[William Rea]

A simple perusal of the other posts on this board should assuage your fears; the only way, other than of course breaking the forum rules, to loose respect on this forum is to repeatedly claim things without legitimate evidence.

If I was in any way interested in gaining your respect then that would bother me.

[MortFurd]

If I was in any way interested in gaining your respect then that would bother me.
What's that matter? Do you forsee a problem in providing evidence that can stand up to scrutiny?

So far, all evidence provided by CTists has tended to evaporate when investigated. Most specifically, Christphera has failed to provide proof of his claimed concrete core and has lost himself in contradication when asked for more information in order to track down the documentary he claism to have seen.

[William Rea]

"I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however," and then you have the gall to complain when other people reply to your posts in a manner for which you don't care? :boggle: Anyone abiding by the stated rules is welcome here; viewpoints regardless. That said, don't expect to be welcomed by everyone in the same way because the open policy applies to all sides and all points of view.

Putting up strawman arguments that I somehow expect different treatment is absurd, I answered a peurile post with a simple direct response. Subsequently I was subjected to a barrage of interventions from amateur moderator wannabe people who had no need to be involved and had no other response than to tell me how rude and like a young upstart I was to answer in such a direct and honest way. I have to ask myself is that really because of a "tone " in the post that simply isn't there? Who is really having the gall? I am looking forward to the similar interventions against Belz for the unecessary flaming post seeing as we are all so fair on here.

I have no problem with opposing points of view but I do not lie down and take **** from idiots without reply. Ah ****, Belz isn't flaming because his/her posts agree with the status quo and a Professional Engineer like myself just deserves everything he gets for being a skeptic. Lol, enjoy the ride.

Are we going to return to the thread topic or is this crap going to continue until a Mod intervenes?

[William Rea]

What's that matter? Do you forsee a problem in providing evidence that can stand up to scrutiny?

So far, all evidence provided by CTists has tended to evaporate when investigated. Most specifically, Christphera has failed to provide proof of his claimed concrete core and has lost himself in contradication when asked for more information in order to track down the documentary he claism to have seen.

I already said in previous posts that I hadn't visited many sites on this subject so you guys have the upper hand over me in knowing all the CT stuff. You all obviously know the arguments from all the CT sites, if you care to read ALL my posts you will notice I am putting forward a personal opinion based upon what I know about Engineering.

I have made no claims about a concrete core, I am not Christophera. I am exploring this subject as we go along. Now the question is are you really open minded enough to make a journey or are you going to spew dogma at me?

[Belz...]

You are as irrelevant to me as your posts. I have no interest in corresponding with you.

My statement stands: you seem to have an overly simplified view of how buildings are built and demolished. Can you defend your assertion ?

I have no idea who Judy Wood is but she is probably saying that if you saw the top of a tree off it topples off because the underlying support is sound. I would not argue with that since the damage to the towers would be akin to cutting them off at the top.

Yes, that it exactly what I am refering to.

[Belz...]

I have no problem with opposing points of view but I do not lie down and take **** from idiots without reply.

Actually you do. You didn't reply to my post.

Ah ****, Belz isn't flaming because his/her posts agree with the status quo and a Professional Engineer like myself just deserves everything he gets for being a skeptic. Lol, enjoy the ride.

You are vastly exaggerating the "flame" in my post. If you truly do believe that the buildings should have toppled like a tree, then you have a cartoon-like vision of what reality is, pure and simple. That's not a flame, that's a statement of fact.

[...] if you care to read ALL my posts you will notice I am putting forward a personal opinion based upon what I know about Engineering.

Which isn't much, admittedly.

[T.A.M.]

William:

I guess I wrongfully expected you to act like most people do when they join a board to discuss things. I was not "acting" like an "amateur moderator wannabe" but that insult is in keeping with your behaviour, so I will accept it as such. Civility and politeness go along way, but play it your way, damned if I give a shiate now.



TAM

[William Rea]

Actually you do. You didn't reply to my post.

You are vastly exaggerating the "flame" in my post. If you truly do believe that the buildings should have toppled like a tree, then you have a cartoon-like vision of what reality is, pure and simple. That's not a flame, that's a statement of fact.

Which isn't much, admittedly.

Irrelevant.

[William Rea]

William:

I guess I wrongfully expected you to act like most people do when they join a board to discuss things. I was not "acting" like an "amateur moderator wannabe" but that insult is in keeping with your behaviour, so I will accept it as such. Civility and politeness go along way, but play it your way, damned if I give a shiate now.



TAM

When you say I should act like most people you say I should show deference to the time servers on here? BS.

Civility and politeness are a two way thing. Apparently not extended to those who disagree with the status quo of the forum. You only have to look at Belz follow ups to see politeness forwarded to someone who has worked as a Professional Engineer for the last 20 years.

As no one else here is able to rise above this I guess the newbie will have to take the lead and return to the thread topic.

[Belz...]

Irrelevant.

Sorry, I'm going to correct that, for you:

Irrelevant I don't like to read posts that disagree with me.

Again: If you truly do believe that the buildings should have toppled like a tree, then you have a cartoon-like vision of what reality is, pure and simple. That's not a flame, that's a statement of fact.

[William Rea]

Sorry, I'm going to correct that, for you:



Again: If you truly do believe that the buildings should have toppled like a tree, then you have a cartoon-like vision of what reality is, pure and simple. That's not a flame, that's a statement of fact.

Irrelevant.

[Belz...]

[...] someone who has worked as a Professional Engineer for the last 20 years.

Are you a structural engineer, sir ?

[Belz...]

Irrelevant.

Oh, please defend yourself. You sound like a punching bag, here.

How is saying your vision of the collapse is incorrect irrelevant ?

[tsig]

No wonder folk here think there was a collapse in NYC on 9-11.
I much prefer getting hit on the head with a bucket of sand than a bucket of gravel or the worst case, a bucket of yesterdays concrete, hardened, and, there is a reason for this that has been completely ignored,

Thanks, I now understand you. I had wondered where you were getting your ideas and I now see that you need to be in hit in the head with a bucket of "yesterdays concrete"
to understand them

[tsig]

I went to 75% of F.R. Greening's document WTCREPORT.pdf and have some serious questions. His excel sheets, values for floor, masses etc will surely be correct. We don't have to reinvent the wheel. I admit that I don't understand everything at the moment (it's been awhile), but if you debug a source code you also don't have to know it completely.

Upper block falls

This is assumed by TV coverage, it does not explain why this happened, apse time you already should take other factors into account, the time could be extremely dependent on these factors or maybe not.

Tacitly assumed that the impulsive delivered by the impact is sufficient to rupture...

Why?

The second stage of collapse

Absolutely relevant for the seismic data, but not really relevant for the speed at which the buildings come down.

For now it is sufficient to note that the collapse times calculated without allowing for E1 are already in reasonable agreement with the observed collapse times.

Of course because this is the theoretical minimum time and that should be near free-fall time because in fact section 3.0 of the paper assumes no resistance in any way, in fact point masses with non-elastic collapses merging into each other without any of the mass moving at an other directory

However, to more precisely model the physics of the WTC collapse events, we need to consider the bending and fracturing energy, E1, that must be expended to collapse each floor

Great but this is still under the assumption of all mass falling down in the same direction to break the next floor.

But the initial kinetic energy Ti is equal to (1/2)Nm_f u^2 so the fractional conversion, fc, of kinetic energy to heat is simply,
fc = Q/Ti = 1/(1 + N)

This is an amazing result IMO, but indeed under the assumption no mass is scattered away from floor N to floor N-1 to ... to floor 1

If we assume 50 % of this energy was available to crush concrete, we have 1.2 x 10^9 J available for WTC 1, and 2.5 x 10^9 J available for WTC 2. This is sufficient to crush the concrete on the impacted floor to 175 micrometer particles. Consider now the newly formed mass of (14 + 1) floors of WTC 1, and (29 + 1) floors of WTC 2, impacting on the floor below.

An amazing amount of energy indeed. Again all crushed concrete is assumed to form a new mass to crush the next floor. Check some videos and detailed pictures, it's absolutely impossible to consider this as a first approximation, the mass scatters in all directions, even upwards. Of course the conservation of mass can't be violated, but the part traveling down together with the initial upperblock is not

(n+1)m_floor

but should be

n m_floor +w m_floor =(n+w)m_floor (**** I wrote it wrong at top)

with w the fraction of the mass traveling downwards. Greening didn't use that, also note that w is not constant, it will be a complicated function (dependent on some variables) for which we only know 0< w<1, it should be estimated.

Further small particles are very sensitive to air resistance and the rest of the crap in the air and the so-called terminal speed is reached very quickly, I'm not sure if the factor w can take that into acount or if another factor is needed for that somewhere. Maybe I'm wrong also now and all these factors seem to have not much influence on the theoretical minimum, but it was just something I thought after reading a little bit.


But now it's time to go out and have some beers, my wife is a little bit angry.. "you should marry with your computer" etc..

In what direction should have the building fell. http://forums.randi.org/images/smilies/confused.gif
:confused:

[tsig]

I was simply making it clear that his post was not welcome and he/she would not elicit a flamed response from me either now or in the future. Quite simple protocol which I didn't realise meant that I should be anything other than firm, would flowery language have made the offence I seem to have caused any less?

Seems like everyone is an amateur moderator on here just itching to intervene.

I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however, If the forum owner doesn't want me here expanding the membership of the forum and eliciting further posts I will happily leave. It seems that already I have generated some traffic from the hostile time servers on the forum.

the martyer syndrome

[William Rea]

If you read back through the posts then you will see that it was you that introduced the tree analogy, NOT ME. I agreed that it was a good analogy to explain to a layman about how the core and trusses worked but put my own limitations on the extent of that analogy. Someone more cynical than me would surmise that you had an agenda bringing trees into it because you probably guessed I knew nothing about this Judy Wood character who it appears has already been the subject of derision on here. Somehow you now think it equates to some kind of point scored over me that I justifiably extended the analogy to suggest that if you cut the top of a tree in a certain plausible way that it tends to topple off the top. If that is too advanced a concept for you then say so because we are really going to have to go back to basics if you don't understand that. This is not about the structure or reaction of wood it is about a law of nature.

My original assertion and subsequent analogy stands.

Relative to other calculations I have seen on here it wouldn't take much. If the forces and energies involved can create pancake then I am pretty sure a topple failure pivoting about the weakened floors is plausible. I saw a photograph on one of these sites where you can actually see the top of the WTC South Tower toppling just before the pancake.

Again it is you getting hung up on trees. You equated density with strength and I showed you that density is not on its own an indicator of such a property. Interestingly wood is porous and not solid as you claim. I would suggest that if you scaled up a tree trunk to the size of the WTC it would look quite porous as well. Secondly as I already pointed out, the fibrous nature of trees gives them their strength and toughness, very much like the fibrous nature of the steel space frame in the WTC.

[tsig]

[QUOTE=William Rea;1909798] Now the question is are you really open minded enough to make a journey or are you going to spew dogma at me?[/QUOTE

What journey? You're already there.

[William Rea]

the martyer syndrome

Another flame from this so called civilised forum I have joined.

Yeah right.

[William Rea]

[quote=William Rea;1909798] Now the question is are you really open minded enough to make a journey or are you going to spew dogma at me?[/QUOTE

What journey? You're already there.

And a personal attack.

I find this amusing considering the lecture I have been given about how civilised this forum is.

Laughable.

[Z]

I didn't request your intervention either.


Yeah, well it's a good thing you're not in charge around here... :D

Just a friendly tip, Billy - it's NEVER a good idea to start bossing people around in threads. You don't own a thread, you can't control who will or will not post in a thread. Fact of the matter is, Belz made a good point, and you don't like it.

Too bad. Grow up.

[kevin]

A testimonial from someone who had talked with a high ranking engineer at otis elevator who described "built to demolish towers", has been completely ignored by the posters of this thread.

http://www.rense.com/general48/chargesplacedinWTC.htm


bigger letters don't make your words true.

That site is down.

I see nothing on your site about otis engineers.

[William Rea]

Yeah, well it's a good thing you're not in charge around here... :D

Just a friendly tip, Billy - it's NEVER a good idea to start bossing people around in threads. You don't own a thread, you can't control who will or will not post in a thread. Fact of the matter is, Belz made a good point, and you don't like it.

Too bad. Grow up.

Strawman.

I'm not bossing anyone around, I'm defending my position firmly. If you can point out ANY single event where I said someone couldn't post in this thread or forum then quote it. Put up or shut up with the strawmen.

Belz didn't make a point. He tried to analogise my opinion with a cartoon the motive of which is clear.

This site is no better than many others where irrational hostility spews forth when you attack the sacred cows of the fundies.

[Z]

I was simply making it clear that his post was not welcome and he/she would not elicit a flamed response from me either now or in the future. Quite simple protocol which I didn't realise meant that I should be anything other than firm, would flowery language have made the offence I seem to have caused any less?

Seems like everyone is an amateur moderator on here just itching to intervene.

I didn't realise I was entering a closed shop where we were all time served apprentices not able to speak until we have done our time. I thought it was an open forum however, If the forum owner doesn't want me here expanding the membership of the forum and eliciting further posts I will happily leave. It seems that already I have generated some traffic from the hostile time servers on the forum.

No, your statement was asanine. If you don't like what someone says, just ignore them. There's no need to tell them to 'buggar off', which, in effect, is what you did.

Like you said, it's an open forum. Which means, you have to accept that people are going to post things you don't want to read or hear. Even in response to your own stupidity.

[Z]

A testimonial from someone who had talked with a high ranking engineer at otis elevator who described "built to demolish towers", has been completely ignored by the posters of this thread.

http://www.rense.com/general48/chargesplacedinWTC.htm

Here is the site that explains how, what that engineer said was done, was actually done.

http://algoxy.com/psych/9-11scenario.html

More lies.

Now, in bold type face!

Chris, this is also a lie. Please provide testimonial of the 'high ranking engineer' himself.

[T.A.M.]

I think this all stems from Belz original "Cartoon" comment, and then your return quip.

His "cartoon" comment was not meant as an insult, but rather was a comment at how things do not behave in the real world like they do with cartoons. I know that appaers obvious, but believe it or not, there are alot of people who come in here and try to convince us of such things, such as the "Cookie Cutter" hole that Flight 77 "should have made" in the Pentagon.

From the start of the ill-tempered postings, all bets were off, and the agression and nasty posts would have come, regardless.

I think if you took the time (and I know you are too busy to do it, and you dont care but..) to look through alot of the threads here, you would find that people who come here with a genuinely inquisitive, as opposed to confrontational attitude, are not treated with hostility.

ANd once again, I am not playing the "moderator wannabe", so get down of your self placed Pedestal, and deal with the ordinary folks that are here Mr. Engineer...

Yours sincerely

Dr. TAM MD, CCFP

[Z]

[quote=DHR;1909875]

And a personal attack.

I find this amusing considering the lecture I have been given about how civilised this forum is.

Laughable.

You started it. You brought this on yourself.

Belz is right - you apparently work in some engineering field that has nothing to do with how buildings work - would that be sanitation engineer, perchance?

This forum responds best to facts and evidence. Snide remarks generally engender more snide remarks, and comments that are counterfactual or lack evidence usually result in immediate and sometimes offensive replies. Your unrealistic understanding of building collapse is cartoonish and over-simplified; Belz stated as much; and in response, you started whining and complaining and basically begging Belz to go away. Since then, all you seem to be doing is whining and complaining about how 'unfairly' you've been treated.

Grow up.

(And prove you're an engineer - or at least, an engineer in a field that has some relevance here.)

[William Rea]

I think this all stems from Belz original "Cartoon" comment, and then your return quip.

His "cartoon" comment was not meant as an insult, but rather was a comment at how things do not behave in the real world like they do with cartoons. I know that appaers obvious, but believe it or not, there are alot of people who come in here and try to convince us of such things, such as the "Cookie Cutter" hole that Flight 77 "should have made" in the Pentagon.

From the start of the ill-tempered postings, all bets were off, and the agression and nasty posts would have come, regardless.

I think if you took the time (and I know you are too busy to do it, and you dont care but..) to look through alot of the threads here, you would find that people who come here with a genuinely inquisitive, as opposed to confrontational attitude, are not treated with hostility.

ANd once again, I am not playing the "moderator wannabe", so get down of your self placed Pedestal, and deal with the ordinary folks that are here Mr. Engineer...

Yours sincerely

Dr. TAM MD, CCFP

TAM, I speak as I find, if someone wants hostility etc I can do sarcasm in spades back. I genuinely pointed out in my posts that I am in effect a virgin to the CT surrounding the WTC and was formulating my own opinions based upon my own knowledge of solid and fluid mechanics. I am more than happy to listen to other opinions but do not expect to be barracked out of the thread. You will notice that once the fundies realised my initial position the attacks blossomed.

I make the offer again that I am more than happy to discuss my opinions but will not tolerate wankers.

I appreciate your attempts to moderate (note the small m) here.

[William Rea]

[quote=William Rea;1909881]

You started it. You brought this on yourself.

Belz is right - you apparently work in some engineering field that has nothing to do with how buildings work - would that be sanitation engineer, perchance?

This forum responds best to facts and evidence. Snide remarks generally engender more snide remarks, and comments that are counterfactual or lack evidence usually result in immediate and sometimes offensive replies. Your unrealistic understanding of building collapse is cartoonish and over-simplified; Belz stated as much; and in response, you started whining and complaining and basically begging Belz to go away. Since then, all you seem to be doing is whining and complaining about how 'unfairly' you've been treated.

Grow up.

(And prove you're an engineer - or at least, an engineer in a field that has some relevance here.)

Irrelevant, and if you can't see why then you need to grow up.

[T.A.M.]

Mature reply...which believe it or not, I actually expected.

I am sure the occasional flame will come, tis expected with life on the boards. You will find that those who debate you vigorously may use some words you may not like, such as "crap" or others, but as you said, you are new to this, they are not. Some of these guys have been here for years debating people, and I guess occasionally they get fed up, but I cant really speak for individuals.

Debate on, and I will resume watching, listening, and learning.

TAM

[T.A.M.]

wrt providing credentials:

They can add weight to ones credibility, but that said, If William Rea is to announce his, than all those debating him should be forced to as well.

TAM

[Arkan_Wolfshade]

Having read about the construction it is my understanding that the core is designed to hold the building up against direct gravity (in compression) and that the envelope of supports that double as the outer wall give the building a moment to resist toppling (compression and tension). the outer walls act as classical buttresses to support the core but the core bears the gravitational forces exerted by itself and the trussed floors.

Regardless of the construction of the core (remember concrete is very good in compression and steel reinforcement is only there to resist tension) I am surprised at the mode of failure for the towers. My expectation would be that the floors would certainly pancake on each other leaving the core remarkably intact and that the top would topple over the core and fall to the side of the building.

http://www.house.gov/science/hot/wtc/wtc-report/WTC_ch2.pdf section 2.2.1.4, 2.2.1.5, 2.2.2.2, and 2.2.2.6 are all directly relevant.

[tsig]

[quote=DHR;1909875]

And a personal attack.

I find this amusing considering the lecture I have been given about how civilised this forum is.

Laughable.

I just asked a question

[TjW]

I have to hand it to Chris; sticking with C4 coated rebar (http://algoxy.com/psych/9-11scenario.html) when he can't actually prove that such a material exists. :covereyes

Here's my theory; they screwed up the order and got chocolate coated rebar instead; the heat of the fire caused melting and shear on the chocolate/concrete line and the towers failed.

No evidence? Hell, I got just as much as Chris has.......:)

Damn terrorist Oompa-Loompas... It was supposed to be high-temperature chocolate.

[tsig]

[quote=DHR;1909875]

And a personal attack.

I find this amusing considering the lecture I have been given about how civilised this forum is.

Laughable.

how was this a personal attack??

[David Wong]

Any time I get in a debate from now on, my entire technique will consist of quoting the previous post and typing the word "irrelevant" under it.

I like that. Saves a bunch of time.

[gumboot]

If you read back through the posts then you will see that it was you that introduced the tree analogy, NOT ME. I agreed that it was a good analogy to explain to a layman about how the core and trusses worked but put my own limitations on the extent of that analogy. Someone more cynical than me would surmise that you had an agenda bringing trees into it because you probably guessed I knew nothing about this Judy Wood character who it appears has already been the subject of derision on here.



Actually, I believe I brought up the trees. You made a comment that you would expect the top of the building to topple over, rather than collapse down through the rest of the building. Judy Wood made the same argument, using trees as an anology. Hence why I brought it up.

I disagree it is a goof way to explain to a layman about the core and trusses. Partly because trees don't have cores and trusses. Also, partly because it's an insult to laymen. I'm a layman. A lot of the NIST report is greek to me. But I can certainly understand the structure of the WTC without delving into plant life.

Not only is it inaccurate, but it's insulting for someone to suggest I'll better understand the structure of the WTC by explaining "well, a skyscraper is like a tree". I'm not five.




I saw a photograph on one of these sites where you can actually see the top of the WTC South Tower toppling just before the pancake.


Actually the top of WTC2 ROTATES as it falls. It isn't tipping. Don't forget the building had to fall through the four or five impact floors before there were any obvious exterior signs of collapse - the impact floors appear to have given way some time before, leaving only the exterior walls which gave way simultaneously.

So as the top collapses through 5 floors (about 60 feet by my calculations) it begins to rotate. Its primary momentum is down, however, not sideways. It is not tipping.




I would suggest that if you scaled up a tree trunk to the size of the WTC it would look quite porous as well. Secondly as I already pointed out, the fibrous nature of trees gives them their strength and toughness, very much like the fibrous nature of the steel space frame in the WTC.


Yes but how many times do we have to repeat that the WTC is mostly AIR? Is a tree mostly air? Or mostly wood? What do you feel offers better structural integrity and resistance to gravitational potential energy, air, or wood?

-Andrew

[einsteen]

The precise calculation should be much more difficult, non-elastic (or inelastic) means in fact that the impuls is conserved but not the energy, it can indeed be used to break a floor or to pulverize some stuff in the building ( I don't care about whether the core is iron or not and how complex the structure is, it's input-output that matters).

But if mass scatters away, obviously, no doubt about it, I'll post a reliable picture from BBC, not from a CT'ers site

http://newsimg.bbc.co.uk/media/images/41497000/jpg/_41497974_wtc_203bap.jpg

Roughly I would say that most of it scatters away from the building and that the block follows it's way down, but as I said the calculation needs to be modified. Greening's paper is without doubt a proper scientific paper, but it is under the assumption of that so-called progressive collapse or whatever the current name is. Some guys made some fun about the "growing block" that I talked about before, but in fact that is what Greening does although the block is in fact the initial falling upperblock plus al mass of the floors collapsed concentrated in a rectangular area (in fact with height=0, like an area of point masses)

This is a mathematical model (ideal situation) of the collapse. If one is able to estimate w(...,.n...,t(n)...)=w(n)? then one can calculate the collapse time. But even without any knowledge about that thing the minimum collapse time will increase, IMO dramatically, but we are not yet at the stage for hard conclusions.

Further the block is assumed to stay intact during its fall by F.R.Greening (it is hard to see from the videos, frames etc what really happened) but if you consider scattering (this means partly elastic and partly inelastic I think) the block will definitely damage during its fall and probably lose some mass during its fall, this is also a thing that should be added to the calculations.

Someone good with excel ? I don't use it I hate it.

[Belz...]

If you read back through the posts then you will see that it was you that introduced the tree analogy, NOT ME.

Again it is you getting hung up on trees.

No, you're the one who said this : "Regardless of the construction of the core (remember concrete is very good in compression and steel reinforcement is only there to resist tension) I am surprised at the mode of failure for the towers. My expectation would be that the floors would certainly pancake on each other leaving the core remarkably intact and that the top would topple over the core and fall to the side of the building. "[/QUOTE]

Gumboot's the one who brought up the tree analogy, because it is essentially what you're saying.

If that is too advanced a concept for you then say so because we are really going to have to go back to basics if you don't understand that.

Actually, I think saying the top should topple to the side pretty much IS an over-simplification of the problem.

[Belz...]

Strawman.

That wasn't a strawman. Get your fallacies straight.

Belz didn't make a point. He tried to analogise my opinion with a cartoon the motive of which is clear.

Of course my motive is clear. I'm calling your BS.

And I'm still waiting for answer to this question:

Are you a structural engineer, sir ?

[gumboot]

The precise calculation should be much more difficult


I'm just curious... what is all this "calculation" intended to determine?

Is the question "is there enough kinetic energy in the building to cause total collapse"?

Because if it is, this seems a bit pointless. The building is made up of a lot of small componants. Each of those componants has gravity acting upon it. The ONLY thing preventing each of those componants from falling to the ground is the overall structural integrity.

As soon as collapse occurs, the upper componants fall on those beneath, disrupting structural integrity. Hence all those componants fall. As they fall they in turn disrupt the structural integrity of the componants beneath.

I really don't see that a great deal of energy is actually REQUIRED.

I think of it like a collection of dominoes. If you take those elaborate structures they create and then knock over, the amount of force required to knock over each of those dominoes independently would be fairly substantial. but you don't. You only need to knock over one. That upsets the structural integrity of the one beside it, so that one topples, and it upsets the integrity of the one beside it, and so on.

You can cause the entire "structure" to completely fail simply by knocking over one.

-Andrew

[Belz...]

But if mass scatters away, obviously, no doubt about it, I'll post a reliable picture from BBC, not from a CT'ers site

http://newsimg.bbc.co.uk/media/images/41497000/jpg/_41497974_wtc_203bap.jpg

Roughly I would say that most of it scatters away from the building and that the block follows it's way down,

Einsteen, you can't simply look at a still from the collapse and guess that "most of [the mass] scatters away from the building". That's just impossible. As usual, you guys try to make your armchair analyses of photos sound authoritative.

[einsteen]

@gumboot

I know the domino stones since I was 8 years old

@Belz

Of course this is some bla bla roughly talk with some pictures, but the factor w should be <1. And please I'm not "you guys", I'm no CT"er, I'm not a conspiray thinker or whatever. I've never been on the Loose Change board only on a Dutch politics board that has a thread in which also everyone believes in

http://frogstar.soylentgeek.com/wav/DAPLANE.WAV

[Belz...]

Of course this is some bla bla roughly talk with some pictures, but the factor w should be <1. And please I'm not "you guys", I'm no CT"er, I'm not a conspiray thinker or whatever.

Doesn't matter. You analysis is consistent with those who embrace that theory: look at pictures, make sense of it using limited skills and knowledge, and then claim that something's amiss.

As far as I can tell from that picture, there could be ANY percentage of the building beign ejected to the side. 1% or 90%. It just isn't conclusive at all.

[einsteen]

Doesn't matter. You analysis is consistent with those who embrace that theory: look at pictures, make sense of it using limited skills and knowledge, and then claim that something's amiss.

As far as I can tell from that picture, there could be ANY percentage of the building beign ejected to the side. 1% or 90%. It just isn't conclusive at all.

Thanks Belz, you admit it could be any percentage, we agree!

[TjW]

No. It can't be "any percentage".
There are values for the mass of the towers. There are values for the mass of the rubble carted away.
Subtract one from the other and you have an upper limit on the mass that was pulverized and blew away as dust, either during the fall or during the cleanup.
Drywall pulverizes more easily than concrete, so the mass of the drywall used in construction should be subtracted from the dust cloud estimate.
Presumably, any force that would crush concrete would also crush drywall.
That will give an upper limit to the amount of pulverized concrete.

It won't tell you how much was crushed to less than 100 microns, but your argument from incredulity seems to stem from pictures of the cleanup that don't have "enough" rubble in them, and pictures of the collapse ejecting clouds of dust.

[Architect]

wrt providing credentials:

They can add weight to ones credibility, but that said, If William Rea is to announce his, than all those debating him should be forced to as well.

TAM

Deal.

BSc(Hons) Upper Second in Architectural Studies
B.Arch in Architecture
RIBA
ARIAS
ARB
FSA Scot (but that's not relevant)

Right, your turn.

[rwguinn]

Deal.

BSc(Hons) Upper Second in Architectural Studies
B.Arch in Architecture
RIBA
ARIAS
ARB
FSA Scot (but that's not relevant)

Right, your turn.

BSME, Mechanical Engineering
Registered Professional Engineer, Colorado
Staff Engineer, major aerospace Co.
Next?

[kevin]

BSME, Mechanical Engineering
Registered Professional Engineer, Colorado
Staff Engineer, major aerospace Co.
Next?

BSEE (Electrical Engineering). I spent 4 years doing electrical engineering mostly doing building power distribution systems. I changed to computer support before taking my PE tests although I had my EIT. I work for a large architectural/engineering consulting firm.

[T.A.M.]

I guess I might as well join in, for what it is worth...

Diploma Electronic Engineering Technology (3 year)
Bachelors of Medical Science (Hons)
MD
CCFP
(Hence why I leave most of the physical science to you guys)

:)
TAM

[GlennB]

I'm just curious... what is all this "calculation" intended to determine?

Is the question "is there enough kinetic energy in the building to cause total collapse"?

Because if it is, this seems a bit pointless. The building is made up of a lot of small componants. Each of those componants has gravity acting upon it. The ONLY thing preventing each of those componants from falling to the ground is the overall structural integrity.

As soon as collapse occurs, the upper componants fall on those beneath, disrupting structural integrity. Hence all those componants fall. As they fall they in turn disrupt the structural integrity of the componants beneath.

Except for the components that are forced outwards and don't make contact with the standing components that remain. This is what einsteen is trying to discuss.

I really don't see that a great deal of energy is actually REQUIRED.

If a CT'er expressed such an opinion here they would be quietly put in their place. "I really don't see..." is just waffle. Have you done the calculations? Please present them.

I think of it like a collection of dominoes. If you take those elaborate structures they create and then knock over, the amount of force required to knock over each of those dominoes independently would be fairly substantial. but you don't. You only need to knock over one. That upsets the structural integrity of the one beside it, so that one topples, and it upsets the integrity of the one beside it, and so on.

So you're likening a 400m steel-framed building, with considerable cross-bracing, to a horizontal line of dominoes each of which is unconnected to its neighbour? Lines of falling dominoes don't accelerate. The analogy is flawed in so many ways it's nearly pointless discussing it.

You can cause the entire "structure" to completely fail simply by knocking over one.

A CT'er would point out that the Windsor building in Madrid suffered some collapse in the upper levels but maintained its integrity.


-Andrew

It's fair to analyse your post the way CT'ers posts get analysed.

[Belz...]

Thanks Belz, you admit it could be any percentage, we agree!

No, we don't, and I'm starting to wonder if your reading ability isn't impaired.

First and foremost, you've forgotten the dots after the "z".

And second, I said it could be any percentage, based only on looking at the picture. You, on the other hand, claim that MOST of the top portion definitely is ejected to the side. I claim that you cannot have such certainty. How you can summise that we agree on this point eludes me.

[Belz...]

wrt providing credentials:

They can add weight to ones credibility, but that said, If William Rea is to announce his, than all those debating him should be forced to as well.

TAM

Master of flame wars. I have no other credentials. I'm just a computer programmer who's equipped with logic and reasoning skills beyond those of a common household rat.

[WildCat]

A CT'er would point out that the Windsor building in Madrid suffered some collapse in the upper levels but maintained its integrity.

And a rational thinker would point out that the Madrid tower was a concrete structure, and the only part that collapsed entirely was the section made of steel.

Madrid supports the accepted view of what happened, not the conspiracy nutter view.

[Belz...]

Except for the components that are forced outwards and don't make contact with the standing components that remain. This is what einsteen is trying to discuss.

REALLY ? That's fascinating. How exactly are they forced outwards if they DON'T make contact with other components ?

If a CT'er expressed such an opinion here they would be quietly put in their place. "I really don't see..." is just waffle. Have you done the calculations? Please present them.

Gumboot is correct: a great deal of energy is NOT required to initiate the collapse, specifically because gravity is a source of tremendous force, in this case, all on its own. All you need is for a single floor to fail.

So you're likening a 400m steel-framed building, with considerable cross-bracing, to a horizontal line of dominoes each of which is unconnected to its neighbour? Lines of falling dominoes don't accelerate. The analogy is flawed in so many ways it's nearly pointless discussing it.

The simplest examples are usually those least understood. His point, if I may, was to illustrate how little energy can be required to initiate a chain reaction.

A CT'er would point out that the Windsor building in Madrid suffered some collapse in the upper levels but maintained its integrity.

Two words: CONCRETE CORE. The only thing that failed at those floors was the STEEL.

[R.Mackey]

It's fair to analyse your post the way CT'ers posts get analysed.
Hello again, GlennB.

In this post (http://forums.randi.org/showpost.php?p=1908739&postcount=3391), down towards the bottom, I showed einsteen how to do a rough calculation to see what percentage of material would have to be totally ejected to make much difference in (a) collapse time or (b) halting collapse entirely.

It's a very large fraction.

At collapse initiation, there is no debris falling away from the structure, since the blocks haven't begun to fragment yet. After initiation, even if every new floor hit was completely ejected, the collapse would still progress, and only slightly slower, according to conservation of momentum.

Greening does not require the upper block remains "intact" as you claim. All he uses is the block's momentum, which is the same regardless of its condition, be it a monolithic chunk or a big pile of baby powder.

It's up to you guys to show otherwise. I support einsteen if he wants to go ahead with this calculation. And please don't use Excel... get help from an academic if you don't know what you're doing.

-----

I guess I'll join in on the "qualification" party --

B.A. Mathematics / B.A. Physics
M.S. Aeronautics
Eng. Aeronautics
10 years at NASA, currently senior technical staff, task manager, and PI

I am not a structural engineer, though I have studied related fields of solid mechanics, FEA, etc.

I'd also prefer you try to find holes in my arguments than worry about my resume. But I am not completely talking out of my hat.

[David Wong]

REALLY ? That's fascinating. How exactly are they forced outwards if they DON'T make contact with other components ?


I believe they think explosives were there in a quantity great enough to actually eject most of the building outward when they detonated.

Which would be a lot.

[Hellbound]

Except for the components that are forced outwards and don't make contact with the standing components that remain. This is what einsteen is trying to discuss.
I don't think anyone is arguing that no material was forced out. In fact, debris was found several blocks away, and buildings damaged in a a large radius.
If a CT'er expressed such an opinion here they would be quietly put in their place. "I really don't see..." is just waffle. Have you done the calculations? Please present them.
True, but we really don't have to get into complex math yet. I'll explain in a moment.
So you're likening a 400m steel-framed building, with considerable cross-bracing, to a horizontal line of dominoes each of which is unconnected to its neighbour? Lines of falling dominoes don't accelerate. The analogy is flawed in so many ways it's nearly pointless discussing it.
Not really pointless, althoguh I'd agree that dominoes are a poor analogy. Tinker Toys or Erector Sets, that might get us somewhere. And the same basic principles apply. You remove some of the supports and braces on the lower parts of the structure (especially with weight and load on the upper portions) and the structure falls. You don't have to have enough energy to move every pice of the structure. Just enough for some supporting members to be removed. The rest of the energy comes from the enormous gravitational potential energy stored in a building.
A CT'er would point out that the Windsor building in Madrid suffered some collapse in the upper levels but maintained its integrity.
Others have pointed this out. The Windsor was a combination steel/concrete structure. Only the concrete portions remained standing, the steel portions collapsed completely.


Now, on the amount of material ejected. We really only have to agree on one aspect to put this pretty well to rest:

Do you believe that the fall of ten floors (the area above the damaged portion in WTC1) has enough energy to collapse one floor?

If the answer is yes, then even assuming 90% of the material is ejected then the collapse will continue progressively throughout the building. 10 floors is roughly 90% of the building. So making a few simplifications (assuming the fllors each had the same mass, etc), then each time it impacted a floor it could eject an amount of mass equal to the entire weight of that floor, and still maintain the same amount of mass as the original impacting section.

[kevin]

Master of flame wars. I have no other credentials. I'm just a computer programmer who's equipped with logic and reasoning skills beyond those of a common household rat.

You forgot to mention you're irrelevant.

[GlennB]

REALLY ? That's fascinating. How exactly are they forced outwards if they DON'T make contact with other components ?

Are you familiar with the concept of "vectors"? You seem to be assuming that anything falling must be falling straight down. A falling item in the collapse might be falling at anywhere from 0 to 89 degrees from the vertical - it's still falling - but will impart varying degrees of its energy to the structures below, depending on the angle of fall.

Gumboot is correct: a great deal of energy is NOT required to initiate the collapse, specifically because gravity is a source of tremendous force, in this case, all on its own. All you need is for a single floor to fail.

This looks like an assertion. I have a film to hand where a multi-storey building was blasted at the base (CD), fell one storey and just sat there, otherwise intact. Is that admissible?

The simplest examples are usually those least understood. His point, if I may, was to illustrate how little energy can be required to initiate a chain reaction.

It's fair to say that falling dominoes was a poor analogy. They don't accelerate.

Two words: CONCRETE CORE. The only thing that failed at those floors was the STEEL.

Accepted, but missing the point. That example was there to illustrate the weakness of impressive but inaccurate comparisons. it was there to weaken the CT argument, not support it (although spalling is an interesting subject that's worth debate)


(why do I have to enter some text outside the quote? ) ;)

[Belz...]

(why do I have to enter some text outside the quote? ) ;)

Because you're not using the quote function properly.

Are you familiar with the concept of "vectors"? You seem to be assuming that anything falling must be falling straight down.

Oh, golly. In order for a vector to exist, the object has to hit SOMETHING.

This looks like an assertion. I have a film to hand where a multi-storey building was blasted at the base (CD), fell one storey and just sat there, otherwise intact. Is that admissible?

I saw that film. I don't know what differences may or may not exist in struture between that building and WTCs 1 and 2, but I know it only fell one floor.

It's fair to say that falling dominoes was a poor analogy. They don't accelerate.

Are you saying that, in the case of the WTC, the effect would be even MORE prominent ?

Accepted, but missing the point.

I'm starting to get tired of reading that particular arrangement of words.

That example was there to illustrate the weakness of impressive but inaccurate comparisons. it was there to weaken the CT argument, not support it (although spalling is an interesting subject that's worth debate)

You said it remained standing, implying that it should have been the case for the WTC. How does this "weaken" the CT argument ?

[Pardalis]

Because you're not using the quote function properly.


I think he knows that. Red makes so much more of an impression...:rolleyes:

[T.A.M.]

It would be a good idea to remember this thread, who ever it was who was talking about doing up a list of intellectuals to oppose the "scholars". Seems like there are quite a few people here who could easily out match them on qualifications alone.

TAM

[GlennB]

I think he knows that. Red makes so much more of an impression...:rolleyes:

That's just childish. I wanted to put my comments next to the appropriate sections of the original post. If you have a preferred colour I'd be happy to oblige. Blue? Green? Yellow? Don't mind.

[Architect]

Hello again, GlennB.


I guess I'll join in on the "qualification" party --

B.A. Mathematics / B.A. Physics
M.S. Aeronautics
Eng. Aeronautics
10 years at NASA, currently senior technical staff, task manager, and PI

I am not a structural engineer, though I have studied related fields of solid mechanics, FEA, etc.

I'd also prefer you try to find holes in my arguments than worry about my resume. But I am not completely talking out of my hat.


So, to summarise there are a good few of us with qualifications absolutely coming out of our ears, postgrad as well as undergrad, and in many cases relevant to the matters at hand. I wonder if Chris and the CT brigade can say the same....

[T.A.M.]

The Scholars have a lot of people with advanced degrees, absolutely. No doubt. A huge percentage of them, particularly in their Full Time Membership, are degrees in areas totally unrelated to the events of 9/11.

I would venture even taking those on this board who have posted theres, and those who haven't, but who possess them, it would be comparative to the list they have of those who are "legitimately" qualified. Thats not to mention those here who are incredibly gifted with common sense, fantastic memories, and great debating skills, along with those of us who have advanced degrees that are in the areas of science, but not directly linked to the physics and engineering fields.

You then take the hundreds involved in NIST, and FEMA well...we all knew that anyway...

Still, if they every question the qualifications of the "JREF" crowd as they call us, we know we can tell them to stuff it.

[Architect]

The Scholars have a lot of people with advanced degrees, absolutely. No doubt. A huge percentage of them, particularly in their Full Time Membership, are degrees in areas totally unrelated to the events of 9/11.



Put it this way. I wouldn't visit my accountant because I had toothache, even if he is degree qualified. :D

[GlennB]

Do you believe that the fall of ten floors (the area above the damaged portion in WTC1) has enough energy to collapse one floor?

Yes, I do. The earlier reference to a building that just sat there after the ground floor was CD'd was of course irrelevant as the remaining structure was perched on solid ground, not the upper 90 storeys of a skyscraper.

If the answer is yes, then even assuming 90% of the material is ejected then the collapse will continue progressively throughout the building. 10 floors is roughly 90% of the building. So making a few simplifications (assuming the fllors each had the same mass, etc), then each time it impacted a floor it could eject an amount of mass equal to the entire weight of that floor, and still maintain the same amount of mass as the original impacting section.

I presume the 90% you quote is a typo and should read 10%. But assuming that then, yes, once the collapse was initiated the building would collapse to the ground. I'm not disputing that. The rate of fall, though, would depend on the rate of loss of material at each floor impact.
(The acceleration observed in the collapse has been explained by an accumulating mass of material that impacts each successive floor, causing that to collapse quicker than the previous floor. If I'm misunderstanding that principle then I'm very happy to be put straight)

This is what einsteen is trying to establish, and coming in for unwarranted slagging off (as we say in the UK) while he's attempting reasonable debate.

.

Is green OK?

[GlennB]

So, to summarise there are a good few of us with qualifications absolutely coming out of our ears, postgrad as well as undergrad, and in many cases relevant to the matters at hand. I wonder if Chris and the CT brigade can say the same....

Tread carefully. That's the way to sophism.
Some "well qualified" bods thought they'd discovered cold fusion a few years ago.

[William Rea]

Mature reply...which believe it or not, I actually expected.

I am sure the occasional flame will come, tis expected with life on the boards. You will find that those who debate you vigorously may use some words you may not like, such as "crap" or others, but as you said, you are new to this, they are not. Some of these guys have been here for years debating people, and I guess occasionally they get fed up, but I cant really speak for individuals.

Debate on, and I will resume watching, listening, and learning.

TAM

TAM, I have voluntarily decided to withdraw from the thread for a while to let the obvious hostility to my opinions recede and let the hot heads cool down a bit. Maybe then you guys can return to discussing what really matters and not go out of your way to be offended by anything I post.

I am not new to debating on forums but as I said I am new to the CT thing because it is something that I don't go out of my way to find on the internet.

I have to say that I trawled through several threads before deciding to join this forum and thought it might be a good place for skeptical debate with adults. it's a real shame that it turns out to be as childish and clique ridden as most other forums including the awful religious fundy sites. The pack mentality of rapid posting someone who is trying to formulate an idea is reprehensible. I have no problem being vigorously questioned about my opinions but I do object to the flaming etc and I despise the intellectual dishonesty of people who do it and then raise their hands saying it wasn't me Guv!

I will be back.

By the way I am a BSc (Hons) in Mechanical Engineering, and for the US people I guess I ought to add that I majored in structural properties of materials. I am a practical rather than academic Engineer hence I did not continue with any formal post graduate studies or research). I am currently working with high temperature non-ferrous superalloys as I have gained an extensive practical knowledge of metallurgy in my 20 years work experience (which I have become expert in despite my original degree being mechanical).

[William Rea]

Put it this way. I wouldn't visit my accountant because I had toothache, even if he is degree qualified. :D

But a Doctor or a vet might be able to help you out mightn't he.

[Architect]

But a Doctor or a vet might be able to help you out mightn't he.

Well that depends upon the cause, doesn't it? If it's an infected abscess then I'm sure they might get it and prescribe antibiotics, but I wouldn't think they could manage fillings or crowns.

Parallel: I understand basic structures, because it is an important part of the architecture curriculum, but frankly I couldn't do the calcs for anything complex. And you wouldn't want the engineer doing the architecture......

[William Rea]

Actually, I believe I brought up the trees....
-Andrew

Isn't that what I said?

:confused:

Did I or didn't I, even Belz is arguing that I didn't bring up the tree analogy when I already stated I didn't. Like I also said, I had no idea that Judy Wood even existed when I made the intial description.

:confused:

You guys are funny.

[Belz...]

Is green OK?

You mean you haven't seen how others use the quote function ?

Yes, I do. The earlier reference to a building that just sat there after the ground floor was CD'd was of course irrelevant as the remaining structure was perched on solid ground, not the upper 90 storeys of a skyscraper.

Trolling, got it.

This is what einsteen is trying to establish, and coming in for unwarranted slagging off (as we say in the UK) while he's attempting reasonable debate.

Ignorance is a valid excuse insofar as one is disposed to getting rid of it.

[William Rea]

Hello again, GlennB.

In this post (http://forums.randi.org/showpost.php?p=1908739&postcount=3391), down towards the bottom, I showed einsteen how to do a rough calculation to see what percentage of material would have to be totally ejected to make much difference in (a) collapse time or (b) halting collapse entirely.

It's a very large fraction.

At collapse initiation, there is no debris falling away from the structure, since the blocks haven't begun to fragment yet. After initiation, even if every new floor hit was completely ejected, the collapse would still progress, and only slightly slower, according to conservation of momentum.

Greening does not require the upper block remains "intact" as you claim. All he uses is the block's momentum, which is the same regardless of its condition, be it a monolithic chunk or a big pile of baby powder.

It's up to you guys to show otherwise. I support einsteen if he wants to go ahead with this calculation. And please don't use Excel... get help from an academic if you don't know what you're doing.

-----

I guess I'll join in on the "qualification" party --

B.A. Mathematics / B.A. Physics
M.S. Aeronautics
Eng. Aeronautics
10 years at NASA, currently senior technical staff, task manager, and PI

I am not a structural engineer, though I have studied related fields of solid mechanics, FEA, etc.

I'd also prefer you try to find holes in my arguments than worry about my resume. But I am not completely talking out of my hat.

One parting comment to make is that although a lot of energy is available it has to be in a useful form to do work i.e. break the preceding floors.

[Belz...]

TAM, I have voluntarily decided to withdraw from the thread for a while to let the obvious hostility to my opinions recede and let the hot heads cool down a bit.

After only 25 posts ? Then might I doubt the following statement:

I am not new to debating on forums

I have to say that I trawled through several threads before deciding to join this forum and thought it might be a good place for skeptical debate with adults. it's a real shame that it turns out to be as childish and clique ridden as most other forums including the awful religious fundy sites.

Oh, please don't bundle the others with me. I'm just cynical, that's all. Most other people here are far more reasonable and open-minded than I am.

The pack mentality of rapid posting someone who is trying to formulate an idea is reprehensible.

That's actually quite funny. As opposed to what you may think, there is little or no pack mentality, here, as far as I can tell. You can check the politics section if you don't believe me. But, everyone can chime in, and if someone, say, you, makes a debatable or controversial comment, you can bet every single one of those individuals is going to speak up.

I will be back.

I honestly don't know whether to say "hopefully" or "unfortunately". I'm going to go with the former, though.

By the way I am a BSc (Hons) in Mechanical Engineering, and for the US people I guess I ought to add that I majored in structural properties of materials. I am a practical rather than academic Engineer hence I did not continue with any formal post graduate studies or research). I am currently working with high temperature non-ferrous superalloys as I have gained an extensive practical knowledge of metallurgy in my 20 years work experience (which I have become expert in despite my original degree being mechanical).

As long as you don't build bridges or high-rise buildings, we're cool.

Did I or didn't I, even Belz is arguing that I didn't bring up the tree analogy when I already stated I didn't. Like I also said, I had no idea that Judy Wood even existed when I made the intial description.

You guys are funny.

Why ? Because both Gumboot and I said the exact same thing and are in agreement with you ?

[William Rea]

That wasn't a strawman. Get your fallacies straight.



Of course my motive is clear. I'm calling your BS.

And I'm still waiting for answer to this question:

Are you a structural engineer, sir ?

Which fallacy is it when you attack an argument that someone has not made?

[William Rea]

Actually the top of WTC2 ROTATES as it falls. It isn't tipping. Don't forget the building had to fall through the four or five impact floors before there were any obvious exterior signs of collapse - the impact floors appear to have given way some time before, leaving only the exterior walls which gave way simultaneously.
-Andrew

Thanks to Arkan for directing me there, check out picture 2.32 at

http://www.house.gov/science/hot/wtc/wtc-report/WTC_ch2.pdf

Noting the picture caption which says the WTC 2 tower top falls to the East and then the South.

[GlennB]

One parting comment to make is that although a lot of energy is available it has to be in a useful form to do work i.e. break the preceding floors.

Exactly. "A big pile of baby powder" would not do the same job as large chunks of concrete+steel, *except* in calculations that only consider total mass.

[Z]

You know, it occurs to me that all this talk of concrete cores, explosives, etc. is a smokescreen to disguise the REAL conspiracy going on: that the towers were impacted by commercial aircraft and fell as the official report says is not nearly as significant as who bin Laden and his terrorists might have really been working for!

IOW, why are all the conspiracies focused on such fantastical, nonsensical concepts such as nonexistent concrete cores and rapid-placed invisible C-4, when very potentially valid concepts like bin Laden being a pawn of the government is simply flatly ignored?

... Just sayin'...

[William Rea]

http://www.house.gov/science/hot/wtc/wtc-report/WTC_ch2.pdf section 2.2.1.4, 2.2.1.5, 2.2.2.2, and 2.2.2.6 are all directly relevant.

As I have stated consistently from the first post I have no problem with the tussed floors between the inner and outer walls pancaking. That seems perfectly rational to me. I don't have a problem with the outer walls peeling since they were designed as buttresses and would be unlikely to be self supporting in the absence of the floor trusses.

The problem that everyone is dancing around is that the central core which was designed to withstand considerable compressive stress should pancake.

Note how they carefully talk in the report about the floors pancaking and the core and outer wall being freestanding.

I will read through it more thoroughly now that someone has directed me there.

Later comment - This is a great report, it seems to bear out everything I have predicted!

[Infinite]

9/11 and those towers falling seemed all alittle staged but who really knows. It seemed like a demolition job. I would think that an airplane exploding into a building would demo more than they actually did. I thought the tops of the buildings would fall off in one peice like a tree falling when cut. The whole building just came down like a demo job though. I find that strange. I find the whole darn thing strange, even the Pentagon. What the heck happened to the airplane that supposedly went into the side of the building? What about the aftermath? Everything is so strange and everyone was so evasive?

[Mr. Skinny]

By the way I am a BSc (Hons) in Mechanical Engineering, and for the US people I guess I ought to add that I majored in structural properties of materials. I am a practical rather than academic Engineer hence I did not continue with any formal post graduate studies or research). I am currently working with high temperature non-ferrous superalloys as I have gained an extensive practical knowledge of metallurgy in my 20 years work experience (which I have become expert in despite my original degree being mechanical).
[slight derail]Mr. Rea, do you mind if I ask you to describe "high temperature non-ferrous superalloys"

Nothing sinister in my question, I assure you. I'm just not used to the term "superalloy" mostly. A couple of examples would probably satisfy my curiousity.[/derail]

[Class]

9/11 and those towers falling seemed all alittle staged but who really knows. It seemed like a demolition job. I would think that an airplane exploding into a building would demo more than they actually did. I thought the tops of the buildings would fall off in one peice like a tree falling when cut. The whole building just came down like a demo job though. I find that strange. I find the whole darn thing strange, even the Pentagon. What the heck happened to the airplane that supposedly went into the side of the building? What about the aftermath? Everything is so strange and everyone was so evasive?
Trees are completely solid objects, the World Trade Center towers have mostly air inside. And the tops of the towers weren't completely cut, they had big holes in them. Structural engineers all agree that the towers fell like they expected them to. The "looked like a controlled demolition" argument is nonsense because the only similarity between a controlled demolition and the WTC collapses was that the towers fell down.

[GlennB]

[slight derail]Mr. Rea, do you mind if I ask you to describe "high temperature non-ferrous superalloys"

Nothing sinister in my question, I assure you. I'm just not used to the term "superalloy" mostly. A couple of examples would probably satisfy my curiousity.[/derail]

About 30 seconds on google should answer your question

[Mr. Skinny]

About 30 seconds on google should answer your question
Perhaps, but I was interested in Mr. Rea's answer, Glenn.

Thanks for trying to help though.

[T.A.M.]

William:
It is too bad it wasn't the experience you were hoping for. I have been talking to a few people about setting up special threads specifically for a single one on one debate. It would have a moderator who would ajudicate any issues, and would make sure only the two who entered the debate were posting, all others could observe only...It is an idea I would like to see occur. I agree, just like when I go into th CT lions den I feel a little overwhelmed, I can see how debating here with so many rapidly posting, can leave one feeling a little "under the microscope". I am not saying you cant handle yourself, I am just saying I know where you are coming from.

Cheers...TAM

INFINITE:

9/11 and those towers falling seemed all alittle staged but who really knows.

The purps know, and for most here, the purps were the 19 hijackers. They staged the attacks alright, and were very successful.


It seemed like a demolition job.
Sounds like an opinion. Won't carry much weight in here unless you can back that statement up with SOLID EVIDENCE.

First, go to Youtube and look up "Landmark tower demolition" then watch an actual "Controlled demolition"...when you get back, look at the following points.

1. Notice how the collapse starts off with a long chain of near continuous flashes and LOUD explosions.
2. This is followed, almost immediately by the building coming straight down BOTTOM FIRST.

Now, go back and look at WTC 1 and 2

Notice:
1. No loud explosions or flashes prior to collapse
2. The collapse begins at the impact zone, not the bottom of the building.


I would think that an airplane exploding into a building would demo more than they actually did.

based on what, an educated guess, and uneducated guess, because apart from the small plane that struck the empire state building many years ago, there were not too many examples of this to compare it with, if any.


I thought the tops of the buildings would fall off in one peice like a tree falling when cut. The whole building just came down like a demo job though. I find that strange.

read through this thread or many others here and you will find solid FACTUAL EVIDENCE AND SCIENCE that will show you why that isn't what should have happened.


I find the whole darn thing strange, even the Pentagon. What the heck happened to the airplane that supposedly went into the side of the building? What about the aftermath? Everything is so strange and everyone was so evasive?

WHo was evasive...show me people being interviewed who evaded the topic. Show me people shying away from making statements.
As for the plane, alot of it disintigrated. The harder, steel and titanium parts did not, and they can be found amongst the wreckage (lots of photos around to confirm it). There are also several large pieces of the plane scattered on the lawn and within the crash site.

happy researching

TAM

[Stellafane]

The is no raw evidence for the steel core columns, A fact proven dozens of times right here in this very thread. I've not lied, you folks paint me as a liar when in fact you support lies.
The only core that can be evidenced with images of the demo is the concrete core (http://algoxy.com/psych/images/southcorestands.gif).

And the only explanaton for near free fall and total pulverization that exists on the web is based on the concrete core. Which is why it's so important to you folks that there was no concrete core.

http://algoxy.com/psych/9-11scenario.html

Nope, you can't get off the hook that easily, liar. You said you saw a BBC/PBS documentary that proves there was a concrete core. No such documentary exists. Therefore you are a liar. Never mind what you think we have or haven't proved. The evidence that you are a liar is stark and unambiguous. You lied, therefore you are a liar -- it's as simple as that. And liars have no credibility at all. Thus Chris, nothing that you say has any significance. That's the price you pay for being a liar. You should have thought of that before you decided to lie.

[R.Mackey]

Exactly. "A big pile of baby powder" would not do the same job as large chunks of concrete+steel, *except* in calculations that only consider total mass.
For you and William Rea, the "big pile of baby powder" would have continued the collapse just fine.

Greening's equation demonstrating that progressive collapse is not only possible but likely, and even matches the observed collapse time pretty well, considers primarily the momentum of the falling mass. That momentum is completely insensitive to the structural integrity of said mass.

I explained this in my earlier post.

[gumboot]

It's fair to analyse your post the way CT'ers posts get analysed.


I completely agree. There is a difference, however. I was asking for clarification about what the discussion is. All I see is an argument from incredulty that an enormous amount of energy is required to produce collapse. I've never actually seen a calculation that determines how much energy is required to collapse a skyscraper. Have you?

Incidentally, I quite frequently make clear that I have only very basic knowledge of structural engineering and what have you. And I mean very basic. You'll notice I do not contribute significantly to such debates, because I do not feel I have the knowledge to do so. I will ask questions of those that know mroe than me, however, because I want to learn.

I will also call foul when people start throwing about photographs as "evidence" (because that's something I DO know about).



Except for the components that are forced outwards and don't make contact with the standing components that remain. This is what einsteen is trying to discuss.


Certainly. I was speaking in generalisations. Would it be true then that the key questions is "What percentage of the debris was forced outwards and did not contribute to subsequent collapse?"?



If a CT'er expressed such an opinion here they would be quietly put in their place. "I really don't see..." is just waffle. Have you done the calculations? Please present them.


As I've said many times, I lack the expertise for such a calculation. Have you done them? How much energy is required to collapse the WTC?

I certainly don't expect my ignorant musings to be held up as any sort of credible argument. Quite the contrary, if I am incorrect, and large amounts of energy ARE required, I would dearly hope my fellow JREFers will put me to rights about that fact.

You are right though, perhaps I should have asked a question, to make it more clear I wasn't trying to produce a solid argument.

So to everyone here, for the benefit of laymen...

1) Am I correct in asserting that failure of structural integrity will result in a structure collapse?
And if yes to above:
2) What magnitude of energy is required to undermine structural integrity of a building like the WTC towers?



So you're likening a 400m steel-framed building, with considerable cross-bracing, to a horizontal line of dominoes each of which is unconnected to its neighbour? Lines of falling dominoes don't accelerate. The analogy is flawed in so many ways it's nearly pointless discussing it.


I think you're exaggerating the significance of the anology. It was an expression of structural integrity, nothing more.




A CT'er would point out that the Windsor building in Madrid suffered some collapse in the upper levels but maintained its integrity.


True. Structural componants certainly do not interact as equally as a collection of dominoes. Some componants are of more importance than others - I would not, for example, to expect a collapsed drywall to bring down the entire WTC.

I merely wanted to point out that a building is a STRUCTURE - not a single entity. It is comprised of many componants that interact. The force required to disrupt integrity of given componants can be very small, but those disrupted componants then disrupt surrounding componants and so on, like a domino. How significant such a disruption will be depends on a number of things.

One of those things is building structure redundancy.

Anecdote time. I'm not sure if you're familiar with the Burj Dubai (http://en.wikipedia.org/wiki/Burj_Dubai)? It is slated to become the tallest building in the world.

The unofficials story of its origins is a little interesting. As you may or may not know, Dubai has poured billions into enormous developments and to do this they have assembled an enormous international team of experts.

Two of those experts were my cousin (a computer graphic artist) and his wife (a civil engineer).

While playing around with various ideas, my cousin and his team produced a computer graphic of a helix shaped skyscraper. Various officials (supposedly including Sheik Al Maktoum himself) rather liked the look of it and decided they wanted it built.

An Australian guy who built the physical models of all the buildings made a model by have a central pillar in a particular shape as a "key" and simply slightly rotating the orientation of the keyhole on each floor, thus creating a helix.

Great for a model. Impossible for actual engineering.

With things heating up in Iraq etc. my cousin and his wife decided to leave (she's now designing a new runway for Heathrow Airport or something...). They left the team doing wind tunnel tests on this skyscraper model. why? They were unsure if the building was even capable of standing up.

Now what was the point of this rambling narrative?

Skyscrapers are not as robust as some here seem to think. Sometimes just getting them to stand up takes some incredible skill. Basic language comprehension is all you need to know that the less stable something is, the easier it is to make it lose that stability.

-Andrew

[gumboot]

The simplest examples are usually those least understood. His point, if I may, was to illustrate how little energy can be required to initiate a chain reaction.


Precisely.

-Andrew

[einsteen]

For you and William Rea, the "big pile of baby powder" would have continued the collapse just fine.

Greening's equation demonstrating that progressive collapse is not only possible but likely, and even matches the observed collapse time pretty well, considers primarily the momentum of the falling mass. That momentum is completely insensitive to the structural integrity of said mass.

I explained this in my earlier post.

Oh yeah, black holes have no hair... and mass is mass of course. Have you read my reply why those collapse times match pretty well ? Because all baby powder is assumed to travel in the same direction, in fact this is a theoretical model where the whole collapse occurs in a space

[0,A] x [0,B] x [0,C]

And the upperblock perfectly fits in it and doesn't allow the baby powder to escape.

Even in this model there wil be scattering (some particles do, some don't), it will bounce back but Greening assumes it just merges and the speed is in the same directory and then we get da funny growin' block again

I would not like it if I get such a block on my head, however if you empty a bucket baby powder on my head, with particles reaching terminal speed quickly I'm fine.

It's a desperate remedy to explain the collapse time.

[gumboot]

Isn't that what I said?

:confused:


No.

You said Belz... brought up the tree analogy. I am Gumboot.

we are different people ;)

-Andrew