faster than free fall

[GodisEnergy]

While the building didnt collapse at freefall speed, Certain parts of the 'collapse' did.
Watch the racing series of explosions travelling down the side of the building,at faster than free fall speed.
http://www.youtube.com/watch?v=qhyu-fZ2nRA

how is this possible without explosives

[Doctor Evil]

It may not be polite, but:

http://www.wtv-zone.com/caseman/3/ani/laughdog.gifhttp://www.wtv-zone.com/caseman/3/ani/laughdog.gif

[Doctor Evil]

Hint; You can clearly see a few small solid chinks, which are not influenced by air drag, falling faster than everything else.

[dtugg]

Edited for Rule 12.

[Quad4_72]

This is really awful. I don't even know what to say to that. GIE, do us a favor and unplug your computer's power supply and cancel your internet service.

[GodisEnergy]

why?

[Hokulele]

why?


As Doctor Evil mentioned, you can see chunks of building material that are falling somewhat slower than free fall (due to air resistance), but are still falling faster than the collapse front (those are not explosions). Ergo, nothing in your video is "faster than free fall".

[GodisEnergy]

yes some parts of the collapse i agree, but there is a part of the collapse a second in where its the other way around

[dtugg]

yes some parts of the collapse i agree, but there is a part of the collapse a second in where its the other way around

What the hell are you talking about?

Faster than free fall? Seriously? Were there rocket engines pointed upwards? There is something wrong with your brain.

[Hokulele]

yes some parts of the collapse i agree, but there is a part of the collapse a second in where its the other way around


And how exactly did you determine this? Show your measurements and calculations that demonstrate what the velocity should have been 1 second into the collapse (hint, 9.806 m/s2), and what is your calculated velocity for the "line of explosions". On this forum, it is pathetically unacceptable to state that it simply looks that way.

[GodisEnergy]

well its faster than the falling debris,
Im trying to figure out how to measure the distance then i can work out the exact speed ,but its hard to see the floors
i was hoping you guys could help ;)

[Hokulele]

well its faster than the falling debris


Again, how did you determine this? Since the debris is not at the same level as the collapse front, how can you tell?

It is not my job to support your assertions. If you cannot provide evidence for your points, it may very well be due to the fact that they are completely wrong.

[Doctor Evil]

I do not know if this help you, GIE, but there are two errors you would want to avoid.

Firstly, you can not assume that all debris will fall in the same manner, due to air resistance. For instance, some panels from the face of the building fall in a way somewhat similar to the way in which a piece of paper would fall. That is, they tumble around. These type of debris clearly fall slower then they would in vacuum.

Look for compact and solid pieces of debris if you want to reduce the effect of drag.

Secondly, do not confuse speed and acceleration. Faster or slower than free fall is a claim about the acceleration of an object, not its speed. As an example, let us assume that during the collapse a piece of material is ejected horizontally from the building.

At the moment that the piece is ejected its vertical component of the velocity is zero, which is slower then the collapse front. However, its acceleration may be that of a free falling object, which is larger than the one of the collapse. As a result its vertical velocity will increase at a larger rate than the one of the front. But, until the time these vertical components of the velocities match, it would lag more and more behind. The crucial point is that this does not mean the front is faster than free fall.

Good night.

[Travis]

A building that falls faster than free fall would be a sign that everything we think we know about physics is just wrong. At that point whether it was a demolition or not becomes rather insignificant.

So what's the point of this claim again?

[Myriad]

Hi GodIsEnergy,

One thing to keep in mind is that all any collapse video can show you is a very small part of what's going on, on the surfaces closest to the camera.

Mathematical models of the collapse describe a step by step process of floors crashing into floors, neatly and evenly like a falling row of dominoes, because that makes the calculations manageable and it's accurate enough to represent limiting cases. People counting frames and pixels on video clips are making that same basic assumption. But the real collapse is more like dumping truckloads of dominoes onto a ski slope and then starting an avalanche. Nothing is happening one step at a time. And you can only see a small part of all that chaotic flow.

So, there might very well be frames in videos that show the outer columns buckling at one floor, and very quickly thereafter (or perhaps even in the same frame), more movement beginning several floors below. That doesn't mean, though, that the first upper movement is the direct cause or the only cause of the movement below. It doesn't mean that the timing of the two events is an accurate measure of the speed of anything falling. One likely possibility is that the interior collapse of the floors might already have progressed past all of those those floors and what you're seeing is several floors worth of of no-longer-supported outer wall giving way more or less all at once.

What you don't see in the videos is any specific object -- whether small piece of debris or large mass of structure -- accelerating at faster than free fall. Nor does the progression of the collapse as a whole, observed on a time and distance scale large enough to smooth out the turbulence of the process, accelerate or travel faster than "free fall speed."

Respectfully,
Myriad

[Hokulele]

A building that falls faster than free fall would be a sign that everything we think we know about physics is just wrong. At that point whether it was a demolition or not becomes rather insignificant.

So what's the point of this claim again?


Well, it may just have been an error in his wording (;)), but it didn't read as if GiE was claiming that the building was collapsing faster than free-fall, but that there was a "line of explosions" moving faster than any debris or the collapse front, assuming "lines of explosions" aren't a gravity-driven event. I was trying to show him (her?) the error of his (her?) ways by having him (her?) try and figure out what the velocity should have been at time t=1 second vs. what it apparently was. Hence the hint about the acceleration due to gravity. Ah well.


ETA: Myriad's answer is better.

[mrbaracuda]

how is this possible without explosives

Uh..

Watch the racing series of explosions

Which is it, GiE? What I see is a "racing series" of air and dust being pushed out by an internal collapse / the upper part crashing down and fires being fueled and pushed out by that air for a second.

How do you explain the very visible fact that the outer walls were pulled inside?

[mrbaracuda]

One likely possibility is that the interior collapse of the floors might already have progressed past all of those those floors and what you're seeing is several floors worth of of no-longer-supported outer wall giving way more or less all at once.

Indeed! :)

[MarkyX]

Someone actually believes that controlled demolition is a supernatural event since it breaks the law of gravity.

Idiots, 9/11 deniers are such *********** idiots.

[Wildy]

Idiots, 9/11 deniers are such *********** idiots.

And you've only just figured this out now?

[rwguinn]

Welcome to 2003.
This BS has been covered in several dozen threads. Do we really need a new one for those too damn lazy to do a tiny bit of research?
I get >10 pages of threads on the issue.
This is trolling, spamming, and incivility all rolled in to 1.
Put the ijits on ignore and let's move on...

[bio]

There are no "squibs" at the corner of the tower.
Why?

[TjW]

There are no "squibs" at the corner of the tower.
Why?

I give up; why?

[tomwaits]

There are no "squibs" at the corner of the tower.
Why?

http://forums.randi.org/imagehosting/21412491718854ca73.jpg

[Trojan]

While the building didnt collapse at freefall speed, Certain parts of the 'collapse' did.
Watch the racing series of explosions travelling down the side of the building,at faster than free fall speed.


how is this possible without explosives

Its not possible to fall faster than free fall speed. To travel downward faster than free fall speed, you would need a force pushing the items downward. How would this occur?

[WildCat]

Its not possible to fall faster than free fall speed. To travel downward faster than free fall speed, you would need a force pushing the items downward. How would this occur?
Why, a Star Wars Space Beam of course!

[beachnut]

While the building didnt collapse at freefall speed, Certain parts of the 'collapse' did.
Watch the racing series of explosions travelling down the side of the building,at faster than free fall speed.
http://www.youtube.com/watch?v=qhyu-fZ2nRA

how is this possible without explosives
Where did you pick up this special science?
Why did you pick the air pressure in your avatar to make up junk science, already discovered by 9/11 truth, and refuted, debunked, and explained with real science?

Air Pressure. oops, it was NWO secret, but gee, science let the beans spill a long time ago.

9/11 truth is in truth, the anti-intellectual side of 9/11, called woo, or nut case ideas on 9/11, 9/11 truth is anything but truth.

You are talking about the air pressure escaping from the building. Fluid dynamics. is a tough subject, but you can see in your avatar, the air is escaping from the WTC collapsing. Did you know light acts like a wave and a particle? If you can explain light, you would not be confused by air pressure.

[Dave Rogers]

While the building didnt collapse at freefall speed, Certain parts of the 'collapse' did.
Watch the racing series of explosions travelling down the side of the building,at faster than free fall speed.
http://www.youtube.com/watch?v=qhyu-fZ2nRA

how is this possible without explosives

The way I see it is this: As the buildings began to fall, parts of the structure impacted on other parts, causing shock waves in the structure below. These travelled downwards through the structure. Because the collapse was chaotic, there would have been multiple different shock waves propagating from different points and bouncing from side to side of the structure at different angles, and at some points multiple shock waves would have interfered constructively. This would strain parts of the structure beyond their limits, causing localised failures. The shock waves, being basically sound waves, would travel downwards at the speed of sound in steel - about 4500 metres per second - much faster than falling debris. There would also have been pressurisation of the lower structure, because of the top part collapsing into it, so any local failure due to elastic waves would result in dust being thrown out of the building where the failures occurred. No physical object is falling faster than freefall (insofar as the phrase has any meaning).

How would you suggest it should be explained, GiE? How is "faster than freefall" possible with explosives?

There are no "squibs" at the corner of the tower.
Why?

For the same reason that there are no squibs anywhere else; there were no special effects explosives or fireworks going off in the collapses.

If you're wondering why there are no ejections of debris at the corners of the towers, of the type erroneously described by some 9/11 truthers as "squibs", using an incorrect term to suggest an inappropriate description of the phenomenon, bear in mind that only about six such occurrences were observed in both collapses together, and the statistics are such that this could be simply coincidence.

Again, bio, why do you think there were no ejecta of debris at the corner of the tower?

Dave

[gumboot]

Guys you're being a bit hasty here to ridicule, and not paying attention to the argument. While I agree whole-heartedly with you about the nonsense of the "faster than freefall" argument, you guys are mostly arguing against a strawman. GodisEnergy is not arguing that material fell faster than freefall. GodisEnergy is arguing that the apparant propagation of the collapse front descends at a rate faster than freefall speed. This would indicate that the propagation of the collapse front was being caused by something other than gravitational force - because gravitational force could only cause it to propagate at a maximum speed of freefall.

Instead, GodisEnergy proposes that timed detonations are occurring one floor after another, and that the timing of these explosives is close enough that the time between one floor detonating and the one below it detonating is less than the time it would take the upper floor to fall that distance.

Thus, if the propagation of the collapse is progressing down the building at a rate that exceeds freefall speed it stands to reason the collapse propagation cannot be driven by gravity and must be driven by a series of local independently initiated failures.

Now, there's lots of flaws in this analysis, the most glaringly obvious being that the collapse doesn't propagate faster than freefall speed, or even close to freefall speed. But let's not argue strawmen here folks - there's no talk of actual objects falling faster than freefall in the OP.

[GodisEnergy]

Guys you're being a bit hasty here to ridicule, and not paying attention to the argument. While I agree whole-heartedly with you about the nonsense of the "faster than freefall" argument, you guys are mostly arguing against a strawman. GodisEnergy is not arguing that material fell faster than freefall. GodisEnergy is arguing that the apparant propagation of the collapse front descends at a rate faster than freefall speed. This would indicate that the propagation of the collapse front was being caused by something other than gravitational force - because gravitational force could only cause it to propagate at a maximum speed of freefall.

Instead, GodisEnergy proposes that timed detonations are occurring one floor after another, and that the timing of these explosives is close enough that the time between one floor detonating and the one below it detonating is less than the time it would take the upper floor to fall that distance.

Thus, if the propagation of the collapse is progressing down the building at a rate that exceeds freefall speed it stands to reason the collapse propagation cannot be driven by gravity and must be driven by a series of local independently initiated failures.

Now, there's lots of flaws in this analysis, the most glaringly obvious being that the collapse doesn't propagate faster than freefall speed, or even close to freefall speed. But let's not argue strawmen here folks - there's no talk of actual objects falling faster than freefall in the OP.

thankyou :cool:

[Grizzly Bear]

Now, there's lots of flaws in this analysis, the most glaringly obvious being that the collapse doesn't propagate faster than freefall speed, or even close to freefall speed. But let's not argue strawmen here folks - there's no talk of actual objects falling faster than freefall in the OP.


The freefall speed arguments needs to wilt anyway.... freefall is motion without any acceleration other than that provided by gravity. For the reasons you put forth and others the argument is DOA, period

[Homeland Insurgency]

What does any of this matter?

Just go to the top of a building and drop a bullet with one hand and at the same time fire a bullet from a gun towards the ground in your other hand.

I think one of them will get there first.

[Thunder]

What does any of this matter?

Just go to the top of a building and drop a bullet with one hand and at the same time fire a bullet from a gun towards the ground in your other hand.

I think one of them will get there first.

if you fire a bullet straight down...from a building, say, 100,000 feet tall..

the bullet will slow down by the friction of the air until it reaches terminal velocity..and will be at the same falling speed as the dropped bullet.

[Earthborn]

how is this possible without explosivesHow is it possible with explosives?

[Mangoose]

I have a question for those with physics/engineering background....

The falling top section of the tower exerts a downward kinetic force on the lower portion of the building. Isn't it reasonable to expect that this energy can be transmitted through the steel structure of the building at a speed quite independent from the speed of gravity? When the collapse initiated, couldn't those at the lobby begin to feel the rumbling?

[Cl1mh4224rd]

What does any of this matter?

Just go to the top of a building and drop a bullet with one hand and at the same time fire a bullet from a gun towards the ground in your other hand.

I think one of them will get there first.


Is that your attempt to explain why the debris falling away from the towers hits the ground faster than the collapse front?

I mean, you do realize that explosives inside the tower exerting a downward force on material inside the tower would not explain the debris outside the tower, because for explosives to eject debris outside of the tower, the force would be applied laterally, therefore not contribute to any downward acceleration... right?

[Doctor Evil]

I have a question for those with physics/engineering background....

The falling top section of the tower exerts a downward kinetic force on the lower portion of the building. Isn't it reasonable to expect that this energy can be transmitted through the steel structure of the building at a speed quite independent from the speed of gravity? When the collapse initiated, couldn't those at the lobby begin to feel the rumbling?

Stresses would indeed propagate at the speed of sound in steel, which is very large. However, in such a case I would expect that a (oversimplified) description of the collapse is as follows: When the top floor impact the bottom one the dynamics stress is transferred fast, but then the closest weak point to the impact zone fail. Then this new chunk of matter falls with the previously falling one, until it hits the next "intact" part. The resulting collapse is rather complicated, but on a large scale still depends on gravity to drive the falling debries.

[Homeland Insurgency]

if you fire a bullet straight down...from a building, say, 100,000 feet tall..

the bullet will slow down by the friction of the air until it reaches terminal velocity..and will be at the same falling speed as the dropped bullet.

The WTC was 100,000 feet tall?

[Homeland Insurgency]

Is that your attempt to explain why the debris falling away from the towers hits the ground faster than the collapse front?

I mean, you do realize that explosives inside the tower exerting a downward force on material inside the tower would not explain the debris outside the tower, because for explosives to eject debris outside of the tower, the force would be applied laterally, therefore not contribute to any downward acceleration... right?

Why don't you tell me what threw columns out sideways fast and hard enough to impale another building hundreds of feet away? Was that just gravity? And why couldn't they be thrown just as fast straight down?

[Grizzly Bear]

Why don't you tell me what threw columns out sideways fast and hard enough to impale another building hundreds of feet away? Was that just gravity? And why couldn't they be thrown just as fast straight down?

A violent and chaotic collapse might be a hint... I'f be interested of course if there really were Hush-a-booms with that much power behind them. Please tell me more about these silent super explosives HI. You seem to have plenty of insight to offer :)

[rwguinn]

I have a question for those with physics/engineering background....

The falling top section of the tower exerts a downward kinetic force on the lower portion of the building. Isn't it reasonable to expect that this energy can be transmitted through the steel structure of the building at a speed quite independent from the speed of gravity? When the collapse initiated, couldn't those at the lobby begin to feel the rumbling?
yep
As a matter of fact, gravity has no beaqring on the problem. That wave is initially going to propagate as a function of the natural frequency of the structural part involved. And that, folks, is strictly a function of mass and stiffness.

[Thunder]

The WTC was 100,000 feet tall?

um...no..they weren't.

[GodisEnergy]

A violent and chaotic collapse might be a hint... I'f be interested of course if there really were Hush-a-booms with that much power behind them. Please tell me more about these silent super explosives HI. You seem to have plenty of insight to offer :)

nano thermite has 2x the explosiveness of rdx

[defaultdotxbe]

nano thermite has 2x the explosiveness of rdx
do you have a source for this?

wouldnt making an incendiary (like thermite) explosive defeat the purpose of an incendiary?

[WildCat]

Why don't you tell me what threw columns out sideways fast and hard enough to impale another building hundreds of feet away? Was that just gravity? And why couldn't they be thrown just as fast straight down?
Is it your contention that columns were thrown hundreds of feet with explosives?

[UNLoVedRebel]

nano thermite has 2x the explosiveness of rdx

What the heck does "2x the explosiveness" mean? Are you talking about Velocity of Detonation (VoD)? RDX's VoD is ~26,000 ft/s, which according to you would make nano thermite ~52,000 ft/s, which is, of course, absurd.

[GodisEnergy]

"certain key MIC (Metastable Intermolecular Composites) characteristics are very attractive and quite promising for practical applications. These include energy output that is 2x that of typical high explosives, the ability to tune the reactive power (10 KW/cc to 10 GW/cc), tunable reaction front velocities of 0.1-1500 meters/sec, and reaction zone temperature exceeding 3000K (equivalent to 2700 Celcius or 5000 Fahrenheit)"

http://ammtiac.alionscience.com/pdf/AMPQ6_1ART06.pdf

[WildCat]

"certain key MIC (Metastable Intermolecular Composites) characteristics are very attractive and quite promising for practical applications. These include energy output that is 2x that of typical high explosives, the ability to tune the reactive power (10 KW/cc to 10 GW/cc), tunable reaction front velocities of 0.1-1500 meters/sec, and reaction zone temperature exceeding 3000K (equivalent to 2700 Celcius or 5000 Fahrenheit)"

http://ammtiac.alionscience.com/pdf/AMPQ6_1ART06.pdf
If you increase the velocity, it's going to make an incredibly loud KABOOM. Low velocity won't eject anything.

[defaultdotxbe]

"certain key MIC (Metastable Intermolecular Composites) characteristics are very attractive and quite promising for practical applications. These include energy output that is 2x that of typical high explosives, the ability to tune the reactive power (10 KW/cc to 10 GW/cc), tunable reaction front velocities of 0.1-1500 meters/sec, and reaction zone temperature exceeding 3000K (equivalent to 2700 Celcius or 5000 Fahrenheit)"

http://ammtiac.alionscience.com/pdf/AMPQ6_1ART06.pdf
energy output is not the same as "explosiveness"

IIRC a stick of butter has more energy than the same weight of dynamite

[Cl1mh4224rd]

Why don't you tell me what threw columns out sideways fast and hard enough to impale another building hundreds of feet away? Was that just gravity?


In a way. It was the force of the falling mass above. Take a piece of pasta, stand it up on end, and slowly push down on it until it breaks. Take note of the tiny pieces that go flying away once that happens.

[TjW]

Why don't you tell me what threw columns out sideways fast and hard enough to impale another building hundreds of feet away? Was that just gravity? And why couldn't they be thrown just as fast straight down?

This seems to be another form of the "building fell within/without it's own footprint" oscillating goalpost:

The collapse was a CD because much of the debris fell straight down, into the building's footprint, and that could only happen with explosives.
The collapse was a CD because so much debris was ejected sideways, outside the building's footprint, and that could only happen with explosives.

[R.Mackey]

energy output is not the same as "explosiveness"

IIRC a stick of butter has more energy than the same weight of dynamite

Measured in terms of actual metabolism, butter has about four times the energy density of dynamite (17 MJ / kg vs. 4.184 MJ / kg), and more than double any known explosive. Common gasoline has about eleven times the energy density.

One pays an enormous penalty in efficiency to get that rapid reaction chemistry.

[Smackety]

In a way. It was the force of the falling mass above. Take a piece of pasta, stand it up on end, and slowly push down on it until it breaks. Take note of the tiny pieces that go flying away once that happens.

dry pasta.

[Trojan]

nano thermite has 2x the explosiveness of rdx

How did you come to this conclusion?

[R.Mackey]

Measured in terms of actual metabolism, butter has about four times the energy density of dynamite (17 MJ / kg vs. 4.184 MJ / kg), and more than double any known explosive. Common gasoline has about eleven times the energy density.

sigh. Correction to the above -- It is TNT that has 4.184 MJ/kg, not dynamite. Dynamite has a slightly higher energy density at about 7.5 MJ/kg.

Compared to dynamite, butter has more than double the energy density. Also, for sake of comparison, most thermite blends average 5-7 MJ/kg as well. All of these exotic materials contain less energy than ordinary combustibles. They just have the ability to release what they have more quickly.

My apologies for any confusion I may have caused. TNT and dynamite are not the same thing, and I should have read more carefully.

[boloboffin]

Need to tear your building down faster than freefall speed? Try new I Can't Believe It's Not Hushaboom!

[lapman]

Did anyone notice how the top section tilts first for almost a half second prior to the collapse? Secondly, as the top section disappears into the dust cloud, there seems to be large sections of perimeter columns peeling away. Are those from the top section or the lower portion of the building?

[jaydeehess]

What does any of this matter?

Just go to the top of a building and drop a bullet with one hand and at the same time fire a bullet from a gun towards the ground in your other hand.

I think one of them will get there first.

As Parky points out they will likely arrive with the same velocity. Personally I do not think it would require a 100,000 foot drop. However since the fired bullet began the trip with an initial velocity greater than zero, the initial velocity of the dropped bullet, it will get there first. In fact it began the trip at a speed greater than that of sound.

In a vacuum, or over a short distance, (thus taking out or minimizing the effect of air resistance) for the fired bullet we have
d1=vit + 0.5at2
whereas for the dropped bullet we have
d2=0.5at2

The difference in distance travelled in a given amount of time will be;
deltad = d1 - d2= (vit + 0.5at2) - (0.5at2)

deltad = vit

Are you telling us that the upper section was fired downward by an explosive force above the hat truss?

Explosives on a floor will exert a force on that floor and on the ceiling of that level. One could, in theory mount a floor wide shaped charge that delivers more downward force than upward force but the effect would be an enormous 'boom' (not observed) and a momentary large change in acelleration (not observed). Besides no one mentioned floor wide explosive carpeting.
Explosives in the floor will result in punching holes in the floor and not contribute to downward acelleration of the building as a whole, just of the bits punched out. "Unshaping" such charges will cause greater fracturing of the concrete but could not increase the downward acelleration.
Explosives on columns might acellerate them outward but could not then also increase downward acelleration. This would also require that there be three charges, one at each end to sever a section of column from the tower, and one more at the center of that section to provide the horizontal 'kick'. (not observed).

[jaydeehess]

nano thermite has 2x the explosiveness of rdx

"certain key MIC (Metastable Intermolecular Composites) characteristics are very attractive and quite promising for practical applications. These include energy output that is 2x that of typical high explosives, the ability to tune the reactive power (10 KW/cc to 10 GW/cc), tunable reaction front velocities of 0.1-1500 meters/sec, and reaction zone temperature exceeding 3000K (equivalent to 2700 Celcius or 5000 Fahrenheit)"

http://ammtiac.alionscience.com/pdf/AMPQ6_1ART06.pdf

A good demonstration of an utter lack of understanding of what you have read.

Thermite releases its energy content much more slowly than 'high explosives'. Gasoline releases it chemical energy content somewhere in between the two but only if very precise conditions of an air/fuel mixture are met. Otherwise it does so much more slowly than thermite.

If you want to have that energy melt something you need the slower release whereas if you want to fracture something you need a very fast release. Its a trade off, high explosives make poor incindiaries, and incindiaries make very poor explosives.

In between you have such things as a fuel/air bomb which is ok for knocking down wood frame buildings and realtively small, non-hardened structures (or people and light vehicles) and lighting them on fire. Its slow for an explosion (pretty much just pushes things around) but pretty fast for an incindiary ( fireball stays in contact with combustibles long enough to heat them to their combustion temperatures).

[jaydeehess]

Explosives on columns might acellerate them outward but could not then also increase downward acelleration. This would also require that there be three charges, one at each end to sever a section of column from the tower, and one more at the center of that section to provide the horizontal 'kick'. (not observed).

I thought about this and its not quite true. One could, in theory, mount explosives such that they impart both a high horz. velocity as well as an initial vert. velocity greater than zero.

However, imparting any downward force on anything that you also want to send hundreds of feet away from the building (disregarding whatever reasoning would be for such a thing) would require that the horizontal force be increased as well.

Now let's understand just what the requirements would be for a supposed demolition involving explosives on the perimeter columns.
One might want to sever a column tree section by blowing it and providing a 'kicker' charge. How big a 'kicker' do you need though? All you really need is for the column tree to move at most, its own width away from the building. Let's say that's 50 cm (I forget just how thick the perimeter columns are). How fast does this have to happen. Well at the initial failure floor it needs to occur no quicker than 0.8 seconds. That's 0.6 meters per second (2.3 KPH) whereas the debris that hit WTC 7 had to have a horizontal velocity of about (IIRC) approx ten times that.
Did the designers decide to load in ten times as much explosive than they would have needed? Why? How did that affect the security involved in such an operation? (harder to hide ten times as much of anything) How was it distributed such that instead of simply 'kicking' it did not re-sever the section? Why did no steel show any sign of explosives having been used?

[roger]

if you fire a bullet straight down...from a building, say, 100,000 feet tall..

the bullet will slow down by the friction of the air until it reaches terminal velocity..and will be at the same falling speed as the dropped bullet.True, and irrelevant to the poster's point. The fired bullet will still reach the ground first, no matter the height.

[uruk]

nano thermite has 2x the explosiveness of rdx

Thermite is not an explosive. It is an incendiary. Thermite is used to burn and melt, not explode.

Somebody just fed you a load of grade a bull hockey.

[PhantomWolf]

sigh. Correction to the above -- It is TNT that has 4.184 MJ/kg, not dynamite. Dynamite has a slightly higher energy density at about 7.5 MJ/kg.

Compared to dynamite, butter has more than double the energy density. Also, for sake of comparison, most thermite blends average 5-7 MJ/kg as well. All of these exotic materials contain less energy than ordinary combustibles. They just have the ability to release what they have more quickly.

My apologies for any confusion I may have caused. TNT and dynamite are not the same thing, and I should have read more carefully.

Tsk Tsk Mackey, Get a clay stabilized nitro-glycerine and a trinitrotoluene mixed up. :p

[R.Mackey]

I's just not really reading. Sorry. There hasn't been a post in the 9/11 Conspiracy Theories subforum, apart from the Physics of Flight edu-thread, that forced me to engage my brain in weeks.

The Truth Movement is several degrees deader and stupider than even my most optimistic predictions. At this point I'd be shocked to get even a single original thought out of them. Peak Truth (http://forums.randi.org/showthread.php?t=83889) apparently was the correct model.

[UNLoVedRebel]

Tsk Tsk Mackey, Get a clay stabilized nitro-glycerine and a trinitrotoluene mixed up. :p

Blame AC/DC for the common misconception that those two explosives are the same.

[Wolrab]

It seems to me that truthers either don't understand or willfully ignore (I could probably end the post here) the speed at which loads are transferred when a column fails. I'm not a scientist or engineer, but I would think the transfer of stress is nearly instantaneous. It's not like the load takes its time to figure out which column it should go to. If the load is too great for the column(s) all that energy is being transferred to, it would fail rather quickly also.

[rwguinn]

It seems to me that truthers either don't understand or willfully ignore (I could probably end the post here) the speed at which loads are transferred when a column fails. I'm not a scientist or engineer, but I would think the transfer of stress is nearly instantaneous. It's not like the load takes its time to figure out which column it should go to. If the load is too great for the column(s) all that energy is being transferred to, it would fail rather quickly also.
Obiously, you have not bee paying attention to those Warner Brothers physics and Wildlife Documentaries.
They prove the TROOF!
You know--where the Coyote tries to catch the Roadrunneer?

[jhunter1163]

I's just not really reading. Sorry. There hasn't been a post in the 9/11 Conspiracy Theories subforum, apart from the Physics of Flight edu-thread, that forced me to engage my brain in weeks.

The Truth Movement is several degrees deader and stupider than even my most optimistic predictions. At this point I'd be shocked to get even a single original thought out of them. Peak Truth (http://forums.randi.org/showthread.php?t=83889) apparently was the correct model.

[own-horn blowing]

Yes, it looks like I was right on the money on that one.

[/own-horn blowing]

[jaydeehess]

It seems to me that truthers either don't understand or willfully ignore (I could probably end the post here) the speed at which loads are transferred when a column fails. I'm not a scientist or engineer, but I would think the transfer of stress is nearly instantaneous. It's not like the load takes its time to figure out which column it should go to. If the load is too great for the column(s) all that energy is being transferred to, it would fail rather quickly also.

This is a concept that Heiwa ignores in his claim that Bazant's calculations of the spring factor in the lower structure is all bogus.

The steel framework will have a spring factor that will act against the force of the impacting mass. But a spring requires time to allow the material to deform, load it too quickly and it will fracture rather than bend.

A illustration of this would be to take a small branch off a tree and slowly bend it. Next bend it as quickly as possible. A slow bend will allow it to bend quite a lot whereas bending it very quickly will likely result in you hearing the cracking of separating fibers.

A steel example; place a small diameter nail in a vise and use a pair of pliers to bend it 90 degrees.
place an indentical small nail in the vise and bring a 2 pound hammer down on it as fast as possible, do it right and you will fracture, rather than bend, the nail despite the fact that the nail would have no problem holding just the gravity load of the hammer and your hand.