Why “The Twin Towers Fell at Free Fall” is The Dumbest Thing I’ve Ever Heard

[delphi_ote]

I'd mentioned I did a basic physics analysis of the WTC collapsing at free fall. Well I finally had time to write it up. Here it is:

http://i71.photobucket.com/albums/i133/delphi_ote/page1.jpg
http://i71.photobucket.com/albums/i133/delphi_ote/page2.jpg

I plan on showing it to the Loosers, but I thought I'd get your comments first.

[Zep]

If I understand it correctly, this is the equivalent of lifting the whole building in its pristine state off the ground a sufficient height for it to attain terminal velocity when dropped, then dropping it. Otherwise it would not have been "free fall". In which case, I can imagine the result would be exactly as you described - a monster bang when it hit!

The reality certainly looked far more like a really tall house of cards falling down, having had a few cards in the middle pulled out. Nothing "free-fall" there.

[ImaginalDisc]

If I understand it correctly, this is the equivalent of lifting the whole building in its pristine state off the ground a sufficient height for it to attain terminal velocity when dropped, then dropping it. Otherwise it would not have been "free fall". In which case, I can imagine the result would be exactly as you described - a monster bang when it hit!

The reality certainly looked far more like a really tall house of cards falling down, having had a few cards in the middle pulled out. Nothing "free-fall" there.

I got that impression I got as well, when I read it the first time. However, I suck at math. Delphi, is d for each floor the same, or the distance from said floor to the ground?

[rwguinn]

Wel done!
Where did it go?
Could that much energy have been absorbed by bending and breaking steel, pulverizing concrete, flinging chunks of stuff into other buildings, and compressing the air between floors?

Another way to do the math is that PE=m*g*h.
That is the real energy available--just as is the kinetic energy. All that energy goes somewhere--and, to put it in layman's terms, things break.
The fact that things break is why it is not free-fall speed-some of the energy is absorbed. The fact that the speed of collapse was near free-fall is due to the huge amount of excess energy over what it took to break stuff.

[Timothy]

To take a CT position in rebuttal to the energy argument:

All the energy went into pulverizing the concrete, steel, etc. when the free-falling chunks hit the ground. It was mostly expended in the process of squashing a 110 story building into a pile approximately 3-4 stories high.

All the explosives did was to separate a relatively small number of structural points throughout the buildings. The free fall is an indication of that.

In the official scenario, where did the energy go? If you claim that it was distributed in each of the floors as pancaking occurred, then the same amount of energy is being released in your scenario as in my scenario....in yours, the energy is released when Floor 78 crashes into Floor 77, which then crashes into Floor 76, etc. In my scenario, the energy is disbursed as Floor 2 freefalls to the ground, immediately followed by Floor 3, then Floor 4, etc.

Exactly the same amount of energy either way.

<end of contrary position>

The energy argument is too simple to adequately explain what's going on, evidenced by the fact that you can make an equally simple counter argument that negates it.

My answer to the "free-fall" argument is "So what?" Unless you can tell me precisely how much time delay is caused by the impact at each floor, I have no basis to think that the whole process wouldn't take approximately as much time as something falling at free-fall. And since I can *see* all the other stuff that's actually falling at free fall outside the buildings, I know that the falling of the building was slightly delayed at each floor.

- Timothy

[rwguinn]

I got that impression I got as well, when I read it the first time. However, I suck at math. Delphi, is d for each floor the same, or the distance from said floor to the ground?
that is the assumption made in the equation. Delphi distributed it equally across the height of the building. It's close enough --likely within a factor of 2 or so. In actuality, buildings typically get lighter as they approach the top since the bottom carries the entire vertical structural load, which, obviously, decreases as you go up. But the difference is not THAT big, since each floor requires the same support underneath it (each floor weighs the same and is the same size as the one below it), which pretty much overshadows the weight of the required vertical support structure

[WildCat]

Nice work Delphi! Can we show that on other sites (giving you full credit, of course)?

[delphi_ote]

I got that impression I got as well, when I read it the first time. However, I suck at math. Delphi, is d for each floor the same, or the distance from said floor to the ground?
d is just the distance between floors in my equations, but the distance each floor falls is taken into account (that's why I had to do the crazy bit with the sum notation in step 6.)

ETA This is clearest in step 5. The kenetic energy for floor 1 is 37,986,135 kJ. Floor 2 is 2*(37,986,135 kJ)

In other words, the final equation is:
(1*37,986,135)+(2*37,986,135)+(3*37,986,135)+(4*37 ,986,135)+... (110*37,986,135)
(which by that nice trick with integers)
= 37,986,135 kJ*(110)(111)/2

[ImaginalDisc]

d is just the distance between floors in my equations, but the distance each floor falls is taken into account (that's why I had to do the crazy bit with the sum notation in step 6.)

Oh, I gotcha. That's where I got confused. Would this be better modeled by calculus?

Of course, I think fewer people understand calculus than algebra.

[Zep]

To take a CT position in rebuttal to the energy argument:

All the energy went into pulverizing the concrete, steel, etc. when the free-falling chunks hit the ground. It was mostly expended in the process of squashing a 110 story building into a pile approximately 3-4 stories high.

All the explosives did was to separate a relatively small number of structural points throughout the buildings. The free fall is an indication of that.

In the official scenario, where did the energy go? If you claim that it was distributed in each of the floors as pancaking occurred, then the same amount of energy is being released in your scenario as in my scenario....in yours, the energy is released when Floor 78 crashes into Floor 77, which then crashes into Floor 76, etc. In my scenario, the energy is disbursed as Floor 2 freefalls to the ground, immediately followed by Floor 3, then Floor 4, etc.

Exactly the same amount of energy either way.

<end of contrary position>

The energy argument is too simple to adequately explain what's going on, evidenced by the fact that you can make an equally simple counter argument that negates it.

My answer to the "free-fall" argument is "So what?" Unless you can tell me precisely how much time delay is caused by the impact at each floor, I have no basis to think that the whole process wouldn't take approximately as much time as something falling at free-fall. And since I can *see* all the other stuff that's actually falling at free fall outside the buildings, I know that the falling of the building was slightly delayed at each floor.

- Timothy
The counter to the counter is to point out an absurdity. You are actually describing the same thing as a card player holding a deck from above, and letting the cards drop to the table one by one from the bottom of the deck.

What they MAY be trying to describe is how a demolition crew take down a building - by removing support at the bottom of the building to cause it to collapse, basically by making it unstable. However all evidence shows in that case the whole building actually moves down as the floors at the bottom collapse. The card-deck equivalent is the sit the deck on the table and remove the cards from the bottom. The top of the deck does not alter in shape, it moves down in toto.

Sense and all the evidence shows that neither of these situations happened at WTC. It collapsed from near the top down. The base was demolished only because the top of the building fell on it!

[delphi_ote]

Nice work Delphi! Can we show that on other sites (giving you full credit, of course)?
Sure, but maybe I should work on clarifying it a bit more? Especially the sigma notation at the end. Only engineers, computer scientists, and math teachers are going to understand that part. :D

[delphi_ote]

Oh, I gotcha. That's where I got confused. Would this be better modeled by calculus?

Of course, I think fewer people understand calculus than algebra.
I did a bit of calculus at the end (assuming the mass was evenly distributed through the structure) but I didn't show my work there because I figured that would be even more confusing. Either way you work it out, the answer is roughly the same.

I'm sure we could go deeper and deeper into the physics of it all, but I think basic Newtonian physics pretty much slam dunks this "free fall" myth.

[ImaginalDisc]

I'm sure we could go deeper and deeper into the physics of it all, but I think basic Newtonian physics pretty much slam dunks this "free fall" myth.

I'm completely with you on that one. I was wondering how accurate that measurement was. Of course, the richter scale is logrythmic, so even if you're off by a factor of 2, it won't matter.

[delphi_ote]

Devil's advocate. Exactly what I was hoping for. :)
All the energy went into pulverizing the concrete, steel, etc. when the free-falling chunks hit the ground. It was mostly expended in the process of squashing a 110 story building into a pile approximately 3-4 stories high.
Unless the structure was slowed as it was falling doing all that crushing, there's still a hell of a lot of energy left over. All this excess energy comes from the impossible velocity that all the pieces would have after free fall when they finally struck the ground. We're still talking about two 4.5 earthquakes in downtown NY.
All the explosives did was to separate a relatively small number of structural points throughout the buildings.
And send them falling with an impossible acceleration.
In the official scenario, where did the energy go? If you claim that it was distributed in each of the floors as pancaking occurred, then the same amount of energy is being released in your scenario as in my scenario....in yours, the energy is released when Floor 78 crashes into Floor 77, which then crashes into Floor 76, etc. In my scenario, the energy is disbursed as Floor 2 freefalls to the ground, immediately followed by Floor 3, then Floor 4, etc.
The energy was distributed into the structure itself, slowing its descent and being released as heat with each inelastic collision between stories.
Exactly the same amount of energy either way.
No it's not. We're talking about dispersing the energy into the structure itself and slowing the collapse down versus letting the entire structure accelerate and build up kinetic energy falling hundreds and hundreds of feet before it hit the ground. By the time it's falling at that velocity, the built up kinetic energy has to go somewhere.
The energy argument is too simple to adequately explain what's going on, evidenced by the fact that you can make an equally simple counter argument that negates it.
If you're dealing with CTs, a simple counter argument negates pretty much any well-reasoned position.
My answer to the "free-fall" argument is "So what?" Unless you can tell me precisely how much time delay is caused by the impact at each floor, I have no basis to think that the whole process wouldn't take approximately as much time as something falling at free-fall. And since I can *see* all the other stuff that's actually falling at free fall outside the buildings, I know that the falling of the building was slightly delayed at each floor.
I think the debris falling at free fall next to the tower is another obvious indication this "free fall" stuff is nonsense.

[aggle-rithm]

I'd mentioned I did a basic physics analysis of the WTC collapsing at free fall. Well I finally had time to write it up. Here it is:



Cool! This includes the solution to a problem I tried to crack a couple of years ago -- the amount of energy released when the towers fell. I wasn't smart and/or persistent enough to finish what I started. The reason I wanted to see those numbers originally was to counter an argument by a CT that more bodies should have been found because the fires in the WTC didn't get hot enough to cremate them. I'm sure there was more than enough energy there to perform what amounted to hundreds of cremations... as unpleasant a thought as that is.

[Timothy]

I'm sure we could go deeper and deeper into the physics of it all, but I think basic Newtonian physics pretty much slam dunks this "free fall" myth.

I don't agree. I haven't doublechecked your math, but your analysis assumes a perfectly elastic collision with the ground for the tranfer of energy. Your analysis would be the equivalent of dropping 110 1-story masses, each from its corresponding n-th height, and each transferring all the energy to the ground. Let's distribute each story to a different location ... at the end you'd be left with a building 1-story high, with an area 110 times as large as a tower footprint.

But that's not what happened. Virtually all 110 stories were pulverized, regardless of what mechanism caused them to fall.

Where did the energy go? (In either case?) Into the inelastic collisions that turned a huge building into a pile of rubble.

This is not a compelling argument. It fails from being too simplistic and making bad assumptions. Perform the same analysis of a top-down pancake using the same assumptions and ask yourself "Where did the energy go?" and I think you'll see the fallacy.

- Timothy

[Manny]

Hope this helps refine things, or at least prepares you for objections.

I was approximately 1 km away. I absolutely felt the collapses. It wasn't strong enough to rattle dishes but there was no mistaking it.

Additionally, you may be underestimating not only the amount of energy which went into pulverizing the floors and their contents but also the amount of mass which did not fall immediately during the collapses. Again ~1 km away (downwind) we had approximately 2" of ejecta (almost entirely a fine powder) outside our building. ~1 km away upwind had 1/8" or so of ejecta.

On the other side, I believe you are using a mass for the towers which presumes them empty. Both towers were essentially fully leased. That's a lot of copiers, file rooms, legal libraries, HVAC equipment, etc.

[delphi_ote]

Cool! This includes the solution to a problem I tried to crack a couple of years ago -- the amount of energy released when the towers fell. I wasn't smart and/or persistent enough to finish what I started. The reason I wanted to see those numbers originally was to counter an argument by a CT that more bodies should have been found because the fires in the WTC didn't get hot enough to cremate them. I'm sure there was more than enough energy there to perform what amounted to hundreds of cremations... as unpleasant a thought as that is.
Not quite, aggle. This is different, because we're assuming the towers didn't hold themselves up at all. The entire mass just fell at once straight to the ground.

This report (http://www.911myths.com/WTCREPORT.pdf) does a better job with the basic physics of the real collapse (in terms of simple physics. There are obviously even better reports released by more technical organizations.)

[delphi_ote]

I don't agree. I haven't doublechecked your math, but your analysis assumes a perfectly elastic collision with the ground for the tranfer of energy. Your analysis would be the equivalent of dropping 110 1-story masses, each from its corresponding n-th height, and each transferring all the energy to the ground. Let's distribute each story to a different location ... at the end you'd be left with a building 1-story high, with an area 110 times as large as a tower footprint.
That's exactly what the CTs are claiming. Look here (http://janedoe0911.tripod.com/BilliardBalls.html) and here (http://www.911blimp.net/prf_FreeFallPhysics.shtml).
But that's not what happened. Virtually all 110 stories were pulverized, regardless of what mechanism caused them to fall.
Obviously that's not what happened. That's why the resulting energy released is so absurd.
Where did the energy go? (In either case?) Into the inelastic collisions that turned a huge building into a pile of rubble.
But there's more of it to deal with if the pieces of the building are allowed to accelerate under free-fall without being slowed crusing the structure. The CTs maintain that there wasn't enough energy in the falling structure to crush the concrete or melt the structure. Those were caused by the explosives, not the kinetic energy. Read more of their claims.
This is not a compelling argument. It fails from being too simplistic and making bad assumptions. Perform the same analysis of a top-down pancake using the same assumptions and ask yourself "Where did the energy go?" and I think you'll see the fallacy.
The report I linked aggle to performs exactly that analysis.

ETA from that report:
One tower contains 48,000,000 kg of concrete, hence energy to crush all of this concrete
to 60 micro m particles:
= 48,000,000 x 6700 J = 3.2 x 10^11 J
and also from that report
The total kinetic energy generated by the collapse of one WTC tower was about
10^12 J.
If you assume inelastic collisions, there's a hell of a lot less energy released.

[delphi_ote]

I was approximately 1 km away. I absolutely felt the collapses. It wasn't strong enough to rattle dishes but there was no mistaking it.
Well it did register around a 2.0 on the Richter scale! I'd expect you guys to feel it out there. But a 4.5 it was not. Clearing that part up would be a good idea, though (i.e. showing how absurd two 4.5 earthquakes in downtown NY is.)
Additionally, you may be underestimating not only the amount of energy which went into pulverizing the floors and their contents
Even accounting for that energy, there's still a huge amount left over.
but also the amount of mass which did not fall immediately during the collapses. Again ~1 km away (downwind) we had approximately 2" of ejecta (almost entirely a fine powder) outside our building. ~1 km away upwind had 1/8" or so of ejecta.
It would be hard to get a figure for exactly how much mass that was, but as you said my figures are for the structure itself, and I'd imagine most of that weight is from the steel (though I haven't actually done any calculations or looked up any sources.)

Edited for clarity.

[money]

Sure, but maybe I should work on clarifying it a bit more? Especially the sigma notation at the end. Only engineers, computer scientists, and math teachers are going to understand that part. :D

Anyone who's taken college stats should understand sigma. This even includes most liberal arts majors, I think. I could be wrong, but I think anyone who is too confused by it won't make it that far down before skipping to your conclusions.

[delphi_ote]

Anyone who's taken college stats should understand sigma. This even includes most liberal arts majors, I think. I could be wrong, but I think anyone who is too confused by it won't make it that far down before skipping to your conclusions.
You're probably right. I just don't want anyone to get the feeling I'm handwaving or intentionally trying to confuse them. Just straightforward equations leading to absurd results.

[Timothy]

That's exactly what the CTs are claiming. Look here (http://janedoe0911.tripod.com/BilliardBalls.html) and here (http://www.911blimp.net/prf_FreeFallPhysics.shtml).


I *love* the detailed, professional looking, colored-charted and MIND-NUMBINGLY STUPID analysis of the first link! I'd relish having the chance to give the author a physics dope-slap!

Every floor apparently dissipates all the energy from each impact and then starts from zero velocity at freefall. That's why it should have taken over a minute and a half to fall ... but, if you choose a smaller pancake interval, you can make the collapse time be anything you want!

- Timothy

[delphi_ote]

I *love* the detailed, professional looking, colored-charted and MIND-NUMBINGLY STUPID analysis of the first link! I'd relish having the chance to give the author a physics dope-slap!
The first was done by an assistant professor of mechanical engineering named Judy Wood (http://www.ces.clemson.edu/me/mefaculty/Wood.html)! She's one of the 9/11 Scholars for Truth group (or whatever they call themselves.)

Every floor apparently dissipates all the energy from each impact and then starts from zero velocity at freefall. That's why it should have taken over a minute and a half to fall ... but, if you choose a smaller pancake interval, you can make the collapse time be anything you want!
That's my favorite bit about that analysis. She imagines the floors actually stopping in mid-air!
:dl:

[Timothy]

delphi_ote

Re: Post #19

You're missing my point.

Consider three cases.

A) 110-story 500,000 t tower collapsing via pancaking, top to bottom
B) 110-story 500,000 t tower destroyed by cutter charges on every floor, everything drops at free-fall.
C) 110 1-story 4500 t rigid blocks magically suspended at appropriate heights over a large area and allowed to free-fall simultaneously on command.

Where does the energy go in each case?

If your calculations are correct, then 2*10^14 J is released in each case. It's all a matter of potential energy. If the mass distribution all started at the same height and wound up all falling down, then the kinetic energy equals the loss of potential energy. Equal in all three cases.

The question you're asking is how much gets coupled into the ground.

I contend that your calculation is the equivalent of case C. Elastic collisions couple an unreasonable amount of energy (2*10^14 J) into the ground in 10 seconds. Sure. No problem there.

But I contend that cases A and B are very similar *to each other* when it comes to where the energy went. Ignore the dispute over the amount of time to collapse ... whether it's 10 seconds or 20 seconds won't matter much to the order of magnitude of the answer. In either case, the potential energy is converted into the kinetic energy that it takes to crush concrete, bend metal, sound, heat, ejecting debris, etc., and whatever is coupled into the ground. If the starting condition and the ending condition are the same, the amount of energy released is the same. If the amount of time to fall is off by a factor of 2, then the power (Energy/time) is off by a factor of 2. But we're not talking factors of 10.

In cases A and B, the amount coupled into the ground must be reduced by a significant amount ... all the other places the energy went. But certainly cases A and B are far more similar to each other than to the simplistic case C.

So, to portray a case C calculation as unreasonably large when one is trying to compare the differences between case A and case B is an obvious fallacy.

The simple approximation does not come anywhere near accurately representing either a pancake collapse or a demolition collapse, hence it's not a compelling argument against a demolition collapse.

- Timothy

[aggle-rithm]

The simple approximation does not come anywhere near accurately representing either a pancake collapse or a demolition collapse, hence it's not a compelling argument against a demolition collapse.

- Timothy

And, granting that the towers fell at free-fall, it's not a compelling argument FOR a demolition collapse, and therefore is irrelevant.

[roger]

To put it more simply: stipulate they (the loosers) are correct. Now:

1) other buildings have been leveled by explosives (fact)

2) the energy of those buildings collapsing did not level every other building 1km around it (fact)

2a) the energy of those buildings collapsing did not cause significant damage to the buildings right beside them (fact)

3) hence, your argument that the WTC could not have been brought down by explosives because every building 1km around would be destroyed by the energy release is clearly wrong* (logic)


* we have never down an explosive demolition of a building as tall as the WTC, but we sure have brought down big ones. One could argue then that 3 is not a solid conclusion since we don't have data for this specific case. True, but I'd want expert testimony by explosive experts stating that it'd be dangerously impossible to bring them down by explosives because of the energy release.

[Gravy]

The first was done by an assistant professor of mechanical engineering named Judy Wood (http://www.ces.clemson.edu/me/mefaculty/Wood.html)! She's one of the 9/11 Scholars for Truth group (or whatever they call themselves.)


That's my favorite bit about that analysis. She imagines the floors actually stopping in mid-air!
:dl:
Anyone notice that Judy Wood has a distinctly Osamaish nose? Coincidence that she's with the CTists?

delphi, I'm a math moron, but your work sure looks purty. I'd love to include it in my new & improved "Loose Change" critique, which will be done today. I'll put a nice frame around it and give it my gold seal of real goodness. That is, if you stand by the math.

When I want to know about the physics behind the collapses, I always turn to the acknowledged expert, Chris Bollyn of the American Free Press:
Evidently the energy source that shook the ground beneath the towers was many times more powerful than the total potential energy released by the falling mass of the towers. The question is, What was that energy source?

[roger]

Now, if you want to combat the "near free fall" argument, you can, and much more simply. The relationship between the acceleration constant, time, and distance is not a linear one. Any comparision between the fall time of the tower and the free fall time as being "very close" is a linear comparision, and hence invalid. The correct computation is to compare the rates of acceleration in each case, not the time.

-----

Or, just show the photographic evidence of the unattached debris falling faster than the floors.

------------

Yes, I know those points have been made to them, and they ignore them. :D

[Anacoluthon64]

Nice work there, but there's an error in the original post that'll get you flamed by the CT losers if they happen upon it.

The speed of a body after falling freely from rest through a distance h is given by Sqrt(2gh), not by Sqrt(2gh)/2 (as given under "Some basic physics equations"). The easiest way to see this is to consider energy conservation - the body of mass m falls through a vertical distance h, converting gravitational potential energy mgh into kinetic energy (in the form of motion) (1/2)mv^2. By energy conservation these two quantities must equal each other.

However, there is a far simpler way to calculate the energy released by the building, again using only energy conservation. Consider a before-and-after situation: from the gravitational potential energy perspective, all that has happened is that the building's centre of mass has dropped through roughly half the initial height of the building (assuming a uniform mass distribution along the building's vertical axis). This is equivalent to the entire building falling through this distance, and it follows that E=Mg(H/2) is the energy released, where M is the mass of the building and H its initial height.

As pointed out elsewhere in this thread, the potential energy considerations, as given, are insufficient on their own to explain the absence of the expected seismicity, air blast, etc. A considerable fraction of the gravitational potential energy was "consumed" in creating new surface area (cracks, fractures, dust) in concrete, bending of steel, displacing trapped air, noise, and several other forms of low-grade energy which ultimately dissipate as irrecoverable heat (entropy). Therefore, the building could not have been in free fall because not all of the gravitational potential energy was available for conversion into energy of motion. Equally important is the fact that the time-rate of energy release (i.e. power) is a better indicator of damage potential or severity than the amount of energy per se.

'Luthon64

[delphi_ote]

Nice work there, but there's an error in the original post that'll get you flamed by the CT losers if they happen upon it.

The speed of a body after falling freely from rest through a distance h is given by Sqrt(2gh), not by Sqrt(2gh)/2 (as given under "Some basic physics equations"). The easiest way to see this is to consider energy conservation - the body of mass m falls through a vertical distance h, converting gravitational potential energy mgh into kinetic energy (in the form of motion) (1/2)mv^2. By energy conservation these two quantities must equal each other.

However, there is a far simpler way to calculate the energy released by the building, again using only energy conservation. Consider a before-and-after situation: from the gravitational potential energy perspective, all that has happened is that the building's centre of mass has dropped through roughly half the initial height of the building (assuming a uniform mass distribution along the building's vertical axis). This is equivalent to the entire building falling through this distance, and it follows that E=Mg(H/2) is the energy released, where M is the mass of the building and H its initial height.

As pointed out elsewhere in this thread, the potential energy considerations, as given, are insufficient on their own to explain the absence of the expected seismicity, air blast, etc. A considerable fraction of the gravitational potential energy was "consumed" in creating new surface area (cracks, fractures, dust) in concrete, bending of steel, displacing trapped air, noise, and several other forms of low-grade energy which ultimately dissipate as irrecoverable heat (entropy). Therefore, the building could not have been in free fall because not all of the gravitational potential energy was available for conversion into energy of motion. Equally important is the fact that the time-rate of energy release (i.e. power) is a better indicator of damage potential or severity than the amount of energy per se.

'Luthon64
Now that's what I call some serious constructive criticism. I'll look into it. :)

ETA I see where I made my mistake with the kinematic equations. That means my final result should be 4 times bigger.

My whole point in this analysis is that if the building isn't crushing itself as it falls and releasing the energy gradually, it's going to have to release it all in a very short time when the floors hit the ground. I want to show how absurd that idea is. I guess I could do some more calculations on the amount of time it would take to hit the ground.

[delphi_ote]

To put it more simply: stipulate they (the loosers) are correct. Now:

1) other buildings have been leveled by explosives (fact)

2) the energy of those buildings collapsing did not level every other building 1km around it (fact)

2a) the energy of those buildings collapsing did not cause significant damage to the buildings right beside them (fact)

3) hence, your argument that the WTC could not have been brought down by explosives because every building 1km around would be destroyed by the energy release is clearly wrong* (logic)


* we have never down an explosive demolition of a building as tall as the WTC, but we sure have brought down big ones. One could argue then that 3 is not a solid conclusion since we don't have data for this specific case. True, but I'd want expert testimony by explosive experts stating that it'd be dangerously impossible to bring them down by explosives because of the energy release.
Buildings brought down by explosives don't fall at free fall either. Using the words "free fall" in this context is absurd.

[CurtC]

To take a CT position in rebuttal to the energy argument:I'm sorry, that was not a very good CT rebuttal at all. I have never seen any of them post something nearly as coherent.

About the pancake theory, by the way, and how Judy Wood thinks each floor should have come to a stop when it hits the one below it, then re-accelerate down to the next one. The pancake idea explains how the collapse was initiated, not how it progressed all the way down. After the first few floors pancaked, a better way to describe what was happening then was an avalanche.

Luthon's post does an excellent job explaining where the energy went, other than kinetic energy moving down.

The CTers are always pointing to the large amount of dust, saying this indicates explosions, but these calculations show that there was vastly more energy available from the falling weight than from any possible explosions, and this energy explains the dust.

[roger]

Buildings brought down by explosives don't fall at free fall either. Using the words "free fall" in this context is absurd.
Then why all the math, if it can be dismissed so easily? If we are going to use math to dismiss a LC hypothesis, apply the math to the claim they make.

Granted, they don't fall at free fall. I haven't seen a claim that it was exactly free fall, and much less than free fall doesn't change the final result much.

Assume it is half free fall. G = 9.8 / 2. given equation 4, that means the ke would be half what you calculated, and given equation 5, the energy released is 1/2 what you calculated (please correct my math if it is wrong).

so, E = 1.16E14, rather than the free fall scenerio of 2.31E14.

Assuming my math above is correct, are you claiming that 1.16E14 is not a significant amount of energy, but 2.31E14 is? That's rhetorical, I'm sure you're not.

[Anacoluthon64]

My whole point in this analysis is that if the building isn't crushing itself as it falls and releasing the energy gradually, it's going to have to release it all in a very short time when the floors hit the ground. I want to show how absurd that idea is.

Yes, this is the point, i.e. the time-rate of energy release, that needs to be "stressed"... ( ;) )

I guess I could do some more calculations on the amount of time it would take to hit the ground.

Hmmm, I think you'd have a hard time convincing the CT-ists of the validity of (some of) the simplifying assumptions you would need to introduce. If their chief argument is dust production, then this is fairly readily refuted on the basis of how the WTC collapsed. In the demolition of buildings by explosives, the building is commonly imploded progressively from top to bottom. The main supporting elements (pillars and central core) are blasted towards the centre of the building (to reduce flyrock leaving the demolition site), and this is done progressively, top-to-bottom, floor-by-floor in a carefully calculated sequence. The delay between floors can be as short as 50 millisec, and as much as 1000 millisec (they get shorter as one goes lower down the building). A floor's set of charges detonate shortly before the falling debris above it hits, thus separating it from the intact part of the building below it, so that the falling debris doesn't impart any energy or momentum to the intact part below.

So what's the upshot of all of the foregoing? Well, if the WTC was "professionally" demolished, one would expect to see a regular succession of clearly discernible dust puffs (generated by the explosives) keeping just ahead of the collapsing zone, at least initially. Such puffs should be forming visibly for several seconds - 110 storeys, you see. Instead, we see a steadily increasing outpouring of dust from the collapse-zone itself, and finally an enormous, billowing dustcloud, both of which are adequately accounted for by the rapidly increasing air blast brought about by the collapsing layers.

What really surprises me is that no CTs have yet been spun about the fact that the debris piles look a bit like pyramids...

'Luthon64

[Starthinker]

I've all but given up on those folks but thought I'd add my thought here. The collaspe of a building is a chaotic event, meaning you can't account for everything. Since the building didn't collaspe from the bottom, you actually have part of the building resisting the collapse as the upper part fell on the bottom part so not all the energy went into colliding with the ground. Not sure how that would work into a math formula but I think it needs to be considered.

Othewise, no matter how you describe it, the CTers will not listen to you.

[Hellbound]

Starthinker:

I believe that's the crux, though. In order for the buildings to fall at "free-fall", you can't have anything resisting thier fall or it won't be freefall anymore.

[Kochanski]

Very cool Delphi, pretty sure a quake of that magnitude would have been felt out in Melville (about 36 miles away) in some sort of way, where I was at the time. We felt nothing.

A quake of that magnitude should have done lots of damage below ground in Manhattan, too. The subways and water mains, gas mains and lots of other things that exist below the streets of Manhattan should have suffered great damage. Tunnels and bridges that are the life line of the city should also have been impacted.

[bjb]

As I recall, there *was* a lot of damage done to the structures beneath the World Trade Centers. Maybe that's where a lot of the energy got absorbed.

[Belz...]

Buildings brought down by explosives don't fall at free fall either. Using the words "free fall" in this context is absurd.

See how good master is ? Planting facts like that ?

He's my role-model. I'm next in line for the post, after all.

[CptColumbo]

The videos I've seen on the collapse of WTC1, one of which is in the begining of Loose Change, you can see large parts falling off to the side. So it's not even an implossion. These parts are also falling faster than the main collapse, so obviously the collapse is slower than free-fall.

[DeVega]

Bumping for Delphi as I'm truly in awe of his maths! (And think it's such an important point/thread!)

[Yllanes]

The energy is (kinetic energy before hitting the ground) = (potential energy before falling) = mgh.

Instead of calculating mgh for each floor and adding all the terms, you can consider all the mass concentrated in the centre of gravity. Thus, the potential energy before falling would be (mass of the whole tower)*g*(half the height of the tower). This should be easier to understand.

Notice that this agrees with your second result, using calculus (if you correct your initial formula and multiply by 4, as another poster already commented).

[Mutton-Head]

Correct me if I'm wrong, but comparing the energy released by the tower falling and the Hiroshima bomb is a fallacy.

The Hiroshima bomb released its approx 7 x 100,000,000,000,000J in less than a second,
Where as the towers released their 2.31 x 100,000,000,000,000J in approx 15 seconds. (Assuming that 450,000,000 kg is correct, which many claim is not.)

Doesn’t this make a big difference?

[Timothy]

Bumping for Delphi as I'm truly in awe of his maths! (And think it's such an important point/thread!)
Unfortunately, there's a fatal math error which renders any usefulness of this calculation moot. Three errors, #2 is the biggie.

1) Error in physics (factor of 4)
2) Error in computation (factor of 1000)
3) Error in reasoning (energy is the same in either case)

1) In the original post:
v = (2gx)^1/2 NOT ((2gx)^1/2)/2
therefore
ke = mgx NOT mgx/4
- This results in an error of a factor of 4 too low

2) In line 5 of the original post, the calculated answer should be in J, NOT kJ.
1(kg*m^2)/(s^2) = 1J, NOT 1kJ
- This results in an error of a factor of 1000 too high

Using the same values for mass, height, I get 9.2*10^11 joules - a percent or two of the Hiroshima atomic bomb.

3) In either case, the *energy* released for a free fall or if they took five minutes to drop is the same, so there's no value in arguing about where the energy went (while there might be some in where the *power* went, but if you're arguing free-fall versus twice the time of free-fall, that's only a factor of two difference inthe answer).

- Timothy

(Edited cause I copied some numbers down wrong)

[delphi_ote]

1) In the original post:
v = (2gx)^1/2 NOT ((2gx)^1/2)/2
therefore
ke = mgx NOT mgx/4
- This results in an error of a factor of 4 too low

Yes. This makes the final answer 4 times larger.
2) In line 5 of the original post, the calculated answer should be in J, NOT kJ.
1(kg*m^2)/(s^2) = 1J, NOT 1kJ
- This results in an error of a factor of 1000 too high

Using the same values for mass, height, I get 2.3*10^11 joules, or 4.6*10^11 for both, which seems to agree fairly closely with
http://news.bbc.co.uk/1/hi/sci/tech/1550326.stm
giving 6.8*10^11 for the entire complex - a percent or two of the Hiroshima atomic bomb.
Indeed. A typo carried on through my results. Don't forget about those orders of magnitude, kids! There's another study in close agreement with the final figure you have there (The Energy Transfer in the WTC Collapse by F.R. Greening) so I'd say that better damn well be the right answer!
3) In either case, the *energy* released for a free fall or if they took five minutes to drop is the same, so there's no value in arguing about where the energy went (while there might be some in where the *power* went, but if you're arguing free-fall versus twice the time of free-fall, that's only a factor of two difference inthe answer).
The energy released is the same, but where the energy went is different. Into the structure itself or into the ground. The towers could not fall at free fall and absorb the energy.

[Pardalis]

Correct me if I'm wrong, but comparing the energy released by the tower falling and the Hiroshima bomb is a fallacy.

The Hiroshima bomb released its approx 7 x 100,000,000,000,000J in less than a second,
Where as the towers released their 2.31 x 100,000,000,000,000J in approx 15 seconds. (Assuming that 450,000,000 kg is correct, which many claim is not.)

Doesn’t this make a big difference?

What fallacy would that be?

[R.Mackey]

I did a similar derivation in the "Loose Change -- Part II" thread, about Page 8... Feel free to check my numbers against yours. Timothy has found the obvious errors, I think. (I came up with 160 tons of TNT equivalent per tower, assuming 500,000 tons mass at start.)

Mutton-Head, I see you never did reply to my calculation, funny to see you here instead. But yes, you are correct, the rapidity of an atomic bomb release compared to ~15 seconds or so does make a difference.

It makes the atomic bomb less efficient in terms of pulverizing materials. So much more energy wasted generating photons and compressing the atmosphere, rather than being concentrated in the structure.

I'm still waiting for any credible reason why we'd need more energy, and why "explosives" is a reasonable source for this vast, previously unnoticed source of energy.

[Lucky]

Delphi_ote:
My advice would be not to pursue this.

1) As several people have pointed out, it's an extremely trivial calculation; just the formula for gravitational potential energy, E = mgx (taking x to be the average distance fallen, i.e. half the height of the building). Your extra working doesn't add anything. There's no need to derive the formula for gravitational energy from kinetic energy and free-fall velocity (why don't these need deriving?); neither is there any point in slicing the mass into floors and then adding them.

2) Your conclusions about the supposed effects of free fall (shaking all the buildings in New York, levelling structures for almost a kilometer) are obviously invalidated by your errors, which make the calculation wrong by a factor of 250.

3) In any case, as Timothy explained, the energy released when an object falls under gravity doesn't depend on it being in free fall; that's a complete red herring. Your calculations (after correction) show that the energy released in falling actually was about 10^12J. Obviously, much of the energy was dissipated as heat without reaching the ground, and some of the debris was scattered widely and took a long time to reach the ground, but I don't suppose anyone disputes this.

Of course, if it wasn't free fall (which it wasn't!) then a lot of the gravitational potential energy of the higher floors was transferred to lower floors during the descent, but some of the effect of that would be to increase the energy with which the lower floors hit the ground. It does seem plausible that in a non-free-fall collapse a much higher proportion of the energy would go towards disrupting the materials of the tower rather than being absorbed by the ground, but your calculation can't demonstrate this.

4) Another problem occurs to me from reading R.Mackey's post and looking at the Greening paper you mentioned. It seems that some CTists are arguing that there must have been explosives because gravitational energy wouldn't be enough to pulverise the towers. Any argument that seeks to minimise the energy released on falling appears to support them.

When the CTists are arguing in opposite directions it's obvious that no calculation can convince them.

[JollyRoger]

All these mathematic and physics theory are wonderfully complex and well thought out, however they do not erase the fact that the ones behind it are still out their, and all the math physics and science has yet to bring them to face what they are responsible for.

People will be talking about this for years, all the how's and why's and what for's. So many theory's, so much damage, so many lives, so many secrets.]
The one thing they can not destroy is the truth, it is the legacy which will out live us all.

We must use all of this knowledge to keep it from happening again, history repeats itself because we have not learned from it.

[ktesibios]

All these mathematic and physics theory are wonderfully complex and well thought out, however they do not erase the fact that the ones behind it are still out their, and all the math physics and science has yet to bring them to face what they are responsible for.


Nineteen of them were obliging enough to kill themselves in the process of committing mass murder. The people directly responsible for funding them and aiding in the planning are probably not that many in number, and IIRC a couple of those are in custody.

It's true that math and physics are less relevant than the arts of the gumshoe in sorting out exactly who done what when and where they are now, but they're quite useful in sorting out reasonable, evidence-supported explanations from paranoid horse patooties.

[delphi_ote]

Delphi_ote:
My advice would be not to pursue this.

1) As several people have pointed out, it's an extremely trivial calculation; just the formula for gravitational potential energy, E = mgx (taking x to be the average distance fallen, i.e. half the height of the building). Your extra working doesn't add anything. There's no need to derive the formula for gravitational energy from kinetic energy and free-fall velocity (why don't these need deriving?); neither is there any point in slicing the mass into floors and then adding them.

2) Your conclusions about the supposed effects of free fall (shaking all the buildings in New York, levelling structures for almost a kilometer) are obviously invalidated by your errors, which make the calculation wrong by a factor of 250.

3) In any case, as Timothy explained, the energy released when an object falls under gravity doesn't depend on it being in free fall; that's a complete red herring. Your calculations (after correction) show that the energy released in falling actually was about 10^12J. Obviously, much of the energy was dissipated as heat without reaching the ground, and some of the debris was scattered widely and took a long time to reach the ground, but I don't suppose anyone disputes this.

Of course, if it wasn't free fall (which it wasn't!) then a lot of the gravitational potential energy of the higher floors was transferred to lower floors during the descent, but some of the effect of that would be to increase the energy with which the lower floors hit the ground. It does seem plausible that in a non-free-fall collapse a much higher proportion of the energy would go towards disrupting the materials of the tower rather than being absorbed by the ground, but your calculation can't demonstrate this.

4) Another problem occurs to me from reading R.Mackey's post and looking at the Greening paper you mentioned. It seems that some CTists are arguing that there must have been explosives because gravitational energy wouldn't be enough to pulverise the towers. Any argument that seeks to minimise the energy released on falling appears to support them.

When the CTists are arguing in opposite directions it's obvious that no calculation can convince them.
You're probably right. My goal was a simple, straightforward analysis. It ended up being a mess. Ah well. I tried. :D

[Mutton-Head]

My only reason for calling the Hiroshima comparison into question, is that metaphors can be misleading.

My intuition tells me that there is more to the real story than either official commission had stated. This is based on 1000 different reasons. It’s been many years since college, so my days are much more dominated by intuition, than by numbers and equations. It would be nice to find a mathematical explanation that was exact. Also, an explanation that went beyond, “The government said so…”
Well, if nothing else, my physics is getting better.

One more comment. You would have to agree, that the mass of material pulverized (material that floated to ground like snow), would have to be subtracted from the amount of mass that actually did the pulverizing, right? Can anyone come up with any reasonable estimates for this? Perhaps based upon the size/shape/speed/density of the cloud? Does anybody put any significance in the fact that it has been described as a “pyroclastic cloud?”

[Arkan_Wolfshade]

My only reason for calling the Hiroshima comparison into question, is that metaphors can be misleading.

My intuition tells me that there is more to the real story than either official commission had stated.
Yes, and this confirmational bias is what prevents you from looking at evidence from a neutral perspective.


This is based on 1000 different reasons.

Top 10?


It’s been many years since college, so my days are much more dominated by intuition, than by numbers and equations. It would be nice to find a mathematical explanation that was exact. Also, an explanation that went beyond, “The government said so…”

I don't think anyone here has been saying that.


Well, if nothing else, my physics is getting better.

One more comment. You would have to agree, that the mass of material pulverized (material that floated to ground like snow), would have to be subtracted from the amount of mass that actually did the pulverizing, right? Can anyone come up with any reasonable estimates for this?

I don't think so. That phrasing suggests that x% of the material was only pulverized, and 100-x% was not.


Perhaps based upon the size/shape/speed/density of the cloud? Does anybody put any significance in the fact that it has been described as a “pyroclastic cloud?”
Just because it may have _looked_ like a pyroclastic flow does not make it one.

[Mutton-Head]

I don't think so. That phrasing suggests that x% of the material was only pulverized, and 100-x% was not.


Perhaps I'm not stating it correctly. Take a block of concrete, measuring 1ft x 1ft x 1ft, siting 200 feet up. Call it block-x. If block-x is completely turned into powder, it will fall to the earth, but may take two minutes to do so. So, it would be safe to say that the mass of block-x did not contribute to breaking steel beams, or pulverizing more concrete, correct?

[Timothy]

Does anybody put any significance in the fact that it has been described as a “pyroclastic cloud?”
The significance is that somebody heard a new phrase on the Discovery channel and decided to use it without actually looking into what it means.

Yes, the material being ejected is a pyroclastic cloud ... if it's made of rock, ash, toxic gas at several hundred degrees C moving at a hundred miles an hour flowing laminarly down the sides of the towers.

Damn, my psychiatrist said I had to stop being sarcastic.

- Timothy

[Mutton-Head]

Just because it may have _looked_ like a pyroclastic flow does not make it one.


Yes, I know this. I know that just because something looks like x, does not necessarily make it x. My question was, does anybody have any info/insight on this. Is it significant? It is meaningless?

[Arkan_Wolfshade]

Perhaps I'm not stating it correctly. Take a block of concrete, measuring 1ft x 1ft x 1ft, siting 200 feet up. Call it block-x. If block-x is completely turned into powder, it will fall to the earth, but may take two minutes to do so. So, it would be safe to say that the mass of block-x did not contribute to breaking steel beams, or pulverizing more concrete, correct?

Not correct, unless you can show that the block absorbed all GPE in its pulverization, which I don't think you can do. Block 1 has to impact something else in order to break apart, in doing so it will impart some KE to whatever it is hitting.

[Mutton-Head]

Yes, and this confirmational bias is what prevents you from looking at evidence from a neutral perspective.

No, I would say it's the fact that I'm human, which makes me biased. I've yet to find one of my species who isn't biased.
I actually am looking at the evidence.

[Mutton-Head]

OK. How about this:

Take all of the dust from the collapse, and condense it back into its original form. Measure its mass. This mass didn’t contribute to the breaking of steel, or pulverizing of concrete.

[Manny]

OK. How about this:

Take all of the dust from the collapse, and condense it back into its original form. Measure its mass. This mass didn’t contribute to the breaking of steel, or pulverizing of concrete.That presupposes that it was all made into dust when that particular floor was impacted by the floor(s) above. In fact, much much more dust was created at impact with the surface (or more properly, the bottom of the pile). For example (http://www.epa.gov/wtc/pictures/pages/02.htm).

[Arkan_Wolfshade]

OK. How about this:

Take all of the dust from the collapse, and condense it back into its original form. Measure its mass. This mass didn’t contribute to the breaking of steel, or pulverizing of concrete.

Think of it this way; take two concrete blocks. Set one on the ground, lift the other one up over your head and drop it on the one sitting on the ground. The KE of the one dropping, as a single mass, contributes to both the stationary and moving blocks breaking apart. The individual granules of concrete that come off of that collision will impart significantly less KE to anything they strike, but they will impart some (note if you get hit by any shrapnel from the experiment that you could feel it hit).

[Mutton-Head]

Think of it this way; take two concrete blocks. Set one on the ground, lift the other one up over your head and drop it on the one sitting on the ground. The KE of the one dropping, as a single mass, contributes to both the stationary and moving blocks breaking apart. The individual granules of concrete that come off of that collision will impart significantly less KE to anything they strike, but they will impart some (note if you get hit by any shrapnel from the experiment that you could feel it hit).

Oh yes, I understand that. All of the mass and energy have to be accounted for.
But I'm specifically talking about Delphi's equation. My question is, how much energy is being directed at destroying the building, and how much "shrapnel" is hitting birds and clouds?

[Mutton-Head]

Isn't it true that Delphi's equation has all of the energy being directed straight down, and, all of the energy contributing to the destruction of the building? But if a steel beam flies away from the building and lands 100 feet away, this beam did no damage to the building.

Isn't this signifigant?

[Manny]

Isn't it true that Delphi's equation has all of the energy being directed straight down, and, all of the energy contributing to the destruction of the building? But if a steel beam flies away from the building and lands 100 feet away, this beam did no damage to the building.

Isn't this signifigant?Yes, Delphi's equation is errant in that respect (which is why he's taking constructive criticism). However, again, a beam landing 100 feet away does not mean that it did no damage. It did no damage after it was ejected from the footprint of the building. A beam which sheared and tumbled from the (just making these figures up) 82nd floor to the 45th before finally hitting something at an angle which ejected it from the building it was still damaging the building that far down.

This is why dynamic modeling is difficult. This is why people can't replicate NIST's finite element analysis on their Dells.

[R.Mackey]

OK. How about this:

Take all of the dust from the collapse, and condense it back into its original form. Measure its mass. This mass didn’t contribute to the breaking of steel, or pulverizing of concrete.
No good. The mass that got turned to dust might not have contributed to any additional breakage after it turned to dust, but it didn't start as dust.

If I take 100 bricks up to the top of a tower, drop each one individually onto a granite surface, smashing every single one of them into dust... I've smashed everything into dust. There's no reason to magically discount that mass.

As others have stated, the overwhelming majority of dust was made at the building/ground interface. There isn't any significant amount of energy being convected away by dust wafting off the stack as it collapses. Even if there was, there is plenty of energy to go around.

[Mutton-Head]

A beam which sheared and tumbled from the (just making these figures up) 82nd floor to the 45th before finally hitting something at an angle which ejected it from the building it was still damaging the building that far down.

Oh yes, of course. So I'm bringing up the point of beams and sh#t that was very visibly ejected immediately away from the tower. Likewise every speck of dust that covered all of Manhattan. My question, to the God of Physics, is, what was the mass of all of that debris?

Also, I’m not knocking Delphi’s math. I can barely even see his math, standing on my tipie-toes. He’s a little bit closer to the God of Physics than myself.

[Mutton-Head]

[QUOTE]As others have stated, the overwhelming majority of dust was made at the building/ground interface.[/QUO

Ah, OK. I guess then I have to specifically ask about the amount that was turned into dust before hitting the ground. You say significant. How significant is significant?

[R.Mackey]

I guess I'm just not making myself clear --

Before the collapse, virtually none of the WTC buildings was in the form of dust. Therefore, any part of the structure turned to dust did so through inelastic collision or grinding with other parts of the structure. It has already contributed to the collapse and fragmentation.

So you cannot neglect the dust.

Any part of the structure that remained standing after any such dust flew away -- even if there was time -- would still fall, and by virtue of its own weight, smash itself to pieces.

Now do you understand?

[Trifikas]

Correct me if I'm wrong on this: (Man, I'm not even CLOSE to being a physics god. I'd be banished to Physics Limbo on my death, I'm so far from it..)


But anything ejected from the towers would stop contributing to the destruction of the towers, but would still have energy and still contribute to the total energy of the system? The Cloud of debris eventually falls to the ground.

[Gravy]

...My intuition tells me that there is more to the real story than either official commission had stated. This is based on 1000 different reasons.My experience with your intuition tells me that your intuition serves you poorly.

It’s been many years since college, so my days are much more dominated by intuition, than by numbers and equations. How about using logic?

It would be nice to find a mathematical explanation that was exact. Also, an explanation that went beyond, “The government said so…” Thanks for another gross oversimplification. The 9/11 investigations were done by thousands of experts working for public and private concerns. Their conclusions are supported by experts worldwide.

Well, if nothing else, my physics is getting better.That's good, but are you really learning nothing else?

One more comment. You would have to agree, Let's stop right there. Using a leading phrase like "You would have to agree" isn't going to help your argument.

...that the mass of material pulverized (material that floated to ground like snow), would have to be subtracted from the amount of mass that actually did the pulverizing, right?I'm glad I didn't "have to agree," because I don't. Your description is another gross oversimplification.

Can anyone come up with any reasonable estimates for this? Perhaps based upon the size/shape/speed/density of the cloud?How would you determine when a "reasonable estimate" is achieved for a difficult problem like this?

Does anybody put any significance in the fact that it has been described as a “pyroclastic cloud?”There's no need to act coy here. Rather than asking us to respond to a random CT quote, why not explain why you think it is significant and ask our opinion of that?

[Hellbound]

Mutton-head:

Let me try this, as you seem to be actually interested in this aspect.

Let's simplify a bit and look at a single block from the roof of the WTC.

The building falls. Part-way down, this block gets eejected, and ends up 100 yards away.

The energy it had has still contributed to the collapse, and the fact that it was ejected is not significant.

"Why?", you may ask? And I'm glad you did...;)

For a piece of debris to be ejected sideways, it must have a force act upon it in two ways: to remove the momentum it had in a downward direction, and another force acting laterally to eject the debris. So, at the point it was ejected, it's energy was already transferred to other parts of the structure (i.e.-it impacted a steel beam, driving that beam downward with a greater force while it was defelcted outward).

It does make a difference, as the energy from the block would be the energy generated during the fall from roof to where ever it was ejected. This means that the initial dust/debris ejected would make the most difference, and dust/debris ejected at lower levels would be exponentially less significant.

All in all, I'd be suprised if the dust and debris ejected amounted to more than 10% of the building's mass (and even that is being generous). And of that 10%, a good majority still added energy to the collapse before being ejected. At best I'd guesstimate a 5% reduction in available energy from ejected debris (just from back of the brain pan calculations).

[Anacoluthon64]

Reading the foregoing posts on the effect of "ejected" dust, steelwork and other detritus, it strikes me that where such material lands is largely irrelevant to the overall energy picture, except insofar as it spreads the total impact energy over a larger area. There is a far more significant aspect to such particulate and deformed constituents: they have subtracted from the total available gravitational potential energy by virtue of becoming separated, torn, bent, twisted, pulverised, comminuted, crushed.

The amount of energy required to bring about each of these effects is considerable (consider the power requirements of crusher and mill installations in ore reduction works, for example, or the energy required to deform a RSJ section - think about how fast the RSJ must be moving to bend on impacting a solid obstacle). Such energy is then no longer available for conversion into kinetic energy of motion, and ultimately impact energy. The energy of motion of a fragment that is flung out sideways is in most cases minuscule compared to the energy it took to become a fragment in the first place.

In the end all of the energy is dissipated in the form of low grade (irrecoverable) heat.

'Luthon64

[Lucky]

You're probably right. My goal was a simple, straightforward analysis. It ended up being a mess. Ah well. I tried. :DLeaving aside the validity or otherwise of the calculation, I must say that introducing more numbers into the confusion seems absolutely the wrong thing to do. Just from following the threads here and an occasional dip into a couple of the barmies’ sites I can see that they love to get their teeth into pointless details, especially numerical ones, as this allows them to ignore the major flaws in their argument.

It’s hard to accept, but cranks tend to know a lot more about their (non) subject than we do, and it’s maddeningly difficult to refute their nonsense with demonstrations of logic; they will just shift the goalposts by introducing some other (non) point that we haven’t heard of or considered.

The only success I’ve ever had with a CTist (it was the ‘moon landings hoax’) was by refusing to discuss any details and getting him to question why he wanted to believe the CT (actually, a strong dose of ridicule helped too, but it was done in a friendly way).

[delphi_ote]

Leaving aside the validity or otherwise of the calculation, I must say that introducing more numbers into the confusion seems absolutely the wrong thing to do. Just from following the threads here and an occasional dip into a couple of the barmies’ sites I can see that they love to get their teeth into pointless details, especially numerical ones, as this allows them to ignore the major flaws in their argument.

It’s hard to accept, but cranks tend to know a lot more about their (non) subject than we do, and it’s maddeningly difficult to refute their nonsense with demonstrations of logic; they will just shift the goalposts by introducing some other (non) point that we haven’t heard of or considered.

The only success I’ve ever had with a CTist (it was the ‘moon landings hoax’) was by refusing to discuss any details and getting him to question why he wanted to believe the CT (actually, a strong dose of ridicule helped too, but it was done in a friendly way).
My goal was to show only that the idea that the towers fell at free fall is completely absurd. I'm tired of hearing that. It's not physically possible. No matter how many explosives you used, no building would fall at free fall.

Even if I had the calculations flawless, it wouldn't dispute any of the CT claims. Just that one ridiculous claim that is made far too often.

[Mutton-Head]

The 9/11 investigations were done by thousands of experts working for public and private concerns. Their conclusions are supported by experts worldwide.

How did these experts determine the temperatures inside the burning floors? I read a transcript of firemen's radio conversations when they reached the burning floors. They seemed to think the fire was relatively minor. They said they would only need two hoses.

[DavidJames]

How did these experts determine the temperatures inside the burning floors? I read a transcript of firemen's radio conversations when they reached the burning floors. They seemed to think the fire was relatively minor. They said they would only need two hoses.Have you read the NIST report?

[Ladewig]

How did these experts determine the temperatures inside the burning floors? I read a transcript of firemen's radio conversations when they reached the burning floors. They seemed to think the fire was relatively minor. They said they would only need two hoses.


I've never heard that. Do you have a citation?

[R.Mackey]

Mutton-Head: Trying to change the subject (again) already?? Does this mean you accept our explanations for the energy of collapse? It's hard to maintain a dialogue if you keep losing focus.

Regarding what you "heard," please show us this transcript so that we can discuss it properly. By itself your recollection proves nothing at all.

In the meantime, there are many ways to establish fire temperature -- forensics (quick example (http://wtc.nist.gov/media/gallery.htm#micro)) and modeling (part of NIST report (http://wtc.nist.gov/progress_report_june04/appendixm.pdf)) are two such ways. There are many others. You should have no trouble at all finding this information.

[Gravy]

How did these experts determine the temperatures inside the burning floors? I read a transcript of firemen's radio conversations when they reached the burning floors. They seemed to think the fire was relatively minor. They said they would only need two hoses.
They reached one floor where fire and impact damage was, as far as we know. That was an amazing feat, Chief Palmer reaching the 78th floor of the south tower, about 13 minutes before collapse. The fires were small on that floor but were raging on the floors above. Just look at the videos. The worst damage was to the 80th floor and above.

I really recommend reading the NIST report.

[kookbreaker]

How did these experts determine the temperatures inside the burning floors? I read a transcript of firemen's radio conversations when they reached the burning floors. They seemed to think the fire was relatively minor. They said they would only need two hoses.

Oh for Pete's sake, have you done any research?!

http://911myths.com/html/no_wtc2_inferno_.html

[Mutton-Head]

Trying to change the subject (again) already?? Does this mean you accept our explanations for the energy of collapse? It's hard to maintain a dialogue if you keep losing focus.

No, actually not trying to change the subject. I felt it wasn't getting anywhere. But that may be entirely my fault. I need to do more external reading.

I am looking at the newer links that you gave me. Thanks.

[Belz...]

No, actually not trying to change the subject. I felt it wasn't getting anywhere.

Doesn't that kinda point to a contradiction, here ?