Judy Wood's "Math"

[Anti-sophist]

I tried to use the search feature and couldn't find anything...

Is there a definitive analysis of her math, anywhere, or just bits and pieces?
http://janedoe0911.tripod.com/BilliardBalls.html
Appendix A

I mean, her opening calculation

If momentum is conserved it can be used to calculate unknown velocities following a collision.

(m1 * v1)i + (m2 * v2)i= (m1 * v1)f + (m2 * v2)f
where the subscript i signifies initial, before the collision, and f signifies final, after the collision.

If (m1)i = 0, and (v2)i = 0, then (v2)f must =0.
So, for conservation of momentum, there cannot be pulverization.




...is incredibly bizarre. Essentially she states that an object at rest colliding with an object of 0 mass will stay at rest. That's a restatement of Newton's First Law. Exactly how does this prove their cannot be pulverization?



Has anyone looked at the rest of this math in any depth?

[uk_dave]

Well it's obvious.....

If a plane really did hit the tower, then, since by the evidence of our own eyes the tower stayed where it was, the plane obviously wasn't moving when it hit the tower. So a plane which is stationary could not cause damage to a tower which is also stationary.

Obviously

[delphi_ote]

Has anyone looked at the rest of this math in any depth?
I looked at her website quite a bit. She's way out to lunch with her math and reasoning. Things like "If there was enough kinetic energy for pulverization, there will be pancaking or pulverization, but not both." :confused:

And her "model" of the collapse is so unrealistic it's absurd. Basically, the floors colliding with each other completely stop the entire collapsing mass.

[jhunter1163]

I know we have some eminently qualified mathematicians here who could take this nonsense apart. I'm not one of them, but I'll lurk and await the debunking. Which I will also read with great glee.

[einsteen]

Her momentum pulverization equation does not really make sense, but what she tries to explain is that pulverized mass doesn't contribute its momentum to the block below. Of course momentum is conserved and will even increase in gravity dP=Fdt. In vacuum the sum of each microparticle's mass times its velocity vector should still be the same but small particles will reach their terminal velocity quickly and do not contribute. I don't really know why the billiard balls are used because that's an elastic situation and the stuff bounces back during the collapse and only the lower ball breaks the next floor and so on. There is no collection of mass in this model. Imo she has a point that you should take pulverization into account and in fact modify Greening's model, but then you should organize your work a little bit and start with step A then B.
And since she is not anonymous I don't get why you use a tripod domain, that doesn't look very professionally.

[T.A.M.]

Her momentum pulverization equation does not really make sense, but what she tries to explain is that pulverized mass doesn't contribute its momentum to the block below. Of course momentum is conserved and will even increase in gravity dP=Fdt. In vacuum the sum of each microparticle's mass times its velocity vector should still be the same but small particles will reach their terminal velocity quickly and do not contribute. I don't really know why the billiard balls are used because that's an elastic situation and the stuff bounces back during the collapse and only the lower ball breaks the next floor and so on. There is no collection of mass in this model. Imo she has a point that you should take pulverization into account and in fact modify Greening's model, but then you should organize your work a little bit and start with step A then B.
And since she is not anonymous I don't get why you use a tripod domain, that doesn't look very professionally.

Did we mention she also believe:

1. The towers are like tall trees, and should have fallen as such.
2. A mini "STAR WARS" Beam was involved in the collapses of the Towers.

and that she uses:

1. Keebler elves

in her talks, and her best mate in this uses:

1. Roadrunner and Coyote cartoons

to explain how the planes should have hit the Towers.

Now does the Tripod thing make more sense...

TAM:D

[einsteen]

Here a combination of noplanes and a mini H-bomb...

http://911-for-dummies.blogspot.com/

Maybe some CT'ers are no real CT'ers but paid by the government to make all CT's look absurd. But that is also a CT isn't it...

[R.Mackey]

Here a combination of noplanes and a mini H-bomb...

http://911-for-dummies.blogspot.com/

Maybe some CT'ers are no real CT'ers but paid by the government to make all CT's look absurd. But that is also a CT isn't it...

Well, at least one poster (http://forums.randi.org/showthread.php?postid=2064698#post2064698) here believes that to be true.

I don't buy it, though. The CT's have demonstrated such overwhelming stupidity, I don't think they need any help. The argument smacks of "that's so insane that it MUST be true" to me -- viz. utterly counter-intuitive.

I also don't see much point looking at her "math" in depth. Her core assumption, that of elastic collisions between floors, is just plain stupid.

[delphi_ote]

Her core assumption, that of elastic collisions between floors, is just plain stupid.
:eek:
The core wasn't steel or concrete. It was rubber!

[Bell]

:eek:
The core wasn't steel or concrete. It was rubber!

And that's the proof no planes hit the towers! If they did, they would have been swung back out! HA!

[R.Mackey]

Her approach is even stupider than I imagined it could be.

This figure, Figure 6 from http://janedoe0911.tripod.com/BilliardBalls.html, shows her collapse time:

http://forums.randi.org/imagehosting/thum_9193454e54fa7c4e9.jpg (http://forums.randi.org/vbimghost.php?do=displayimg&imgid=2422)

Each of those colored lines is meant to represent the trajectory of a single WTC floor.

You'll notice they all start from rest, and all accelerate at a constant rate (gravity).

In other words, Woods is assuming that when falling floors hit floors below, they impart no energy at all to the floors below -- merely break them loose.

In reality, the falling upper pile of debris not only breaks lower sections loose, but also imparts momentum, and this momentum increases as the collapse progresses.

I'd fail this report in a junior high physics class.

[delphi_ote]

In other words, Woods is assuming that when falling floors hit floors below, they impart no energy at all to the floors below -- merely break them loose.
Exactly. The entire mass stops in mid-air!

[beachnut]

Her approach is even stupider than I imagined it could be.

This figure, Figure 6 from http://janedoe0911.tripod.com/BilliardBalls.html, shows her collapse time:

http://forums.randi.org/imagehosting/thum_9193454e54fa7c4e9.jpg (http://forums.randi.org/vbimghost.php?do=displayimg&imgid=2422)

Each of those colored lines is meant to represent the trajectory of a single WTC floor.

You'll notice they all start from rest, and all accelerate at a constant rate (gravity).

In other words, Woods is assuming that when falling floors hit floors below, they impart no energy at all to the floors below -- merely break them loose.

In reality, the falling upper pile of debris not only breaks lower sections loose, but also imparts momentum, and this momentum increases as the collapse progresses.

I'd fail this report in a junior high physics class.

I think people have problems with a floor failing and having an instantaneous velocity of the new total mass, based on the impact mass momentum minus the energy to cause failure.

There are no stops once the energy available causes all below to fail.

[R.Mackey]

I think people have problems with a floor failing and having an instantaneous velocity of the new total mass, based on the impact mass momentum minus the energy to cause failure.

There are no stops once the energy available causes all below to fail.
To be utterly pedantic, not "instantaneous," of course. When the two masses hit, there is some compression of steel and concrete, the impact behaving as a pressure wave travelling at the speed of sound in materials, and then the new combined mass equilibrates at its new velocity.

But pretty darn close to instantaneous. The process would be over in milliseconds.

Just trying to anticipate the next complaint. You can never be too accurate when dealing with these people -- their anomaly detectors are set on hair triggers.

[T.A.M.]

so a more accurate analogy than billiard balls hitting one off the other in succession, would be one billiard ball hitting the next, the two moving together, faster than the first, than this small train hits a third, the three moving faster still, this train hits a fourth, and so on...

TAM

[Mashuna]

I don't have any kind of engineering background, but is this just an example of people getting confused by Zeno's paradox? They posit an instant where the floor falling meets the floor that is still in place, and there must be an instant when the momentum is transferred. At that point, they reset all the calculations.

The argument that Woods presents (which I may have misunderstood entirely) reads to me like an attempt to disprove a physical event from (misapplied) logical principles.

[delphi_ote]

The argument that Woods presents (which I may have misunderstood entirely) reads to me like an attempt to disprove a physical event from (misapplied) logical principles.
In a sense, yes. She's forgetting about all about the kinetic energy mass above the collision. Rather than crashing into the floor below and adding its kinetic energy to the combined falling mass, she invents a fantasy where the mass hits the floor below and completely stops. It then patiently waits for the floor below to accelerate from 0 velocity until they hit the next floor.

Any wonder why she gets a figure of a minute and a half for the building to collapse?!

[Mashuna]

In a sense, yes. She's forgetting about all about the kinetic energy mass above the collision. Rather than crashing into the floor below and adding its kinetic energy to the combined falling mass, she invents a fantasy where the mass hits the floor below and completely stops. It then patiently waits for the floor below to accelerate from 0 velocity until they hit the next floor.

Any wonder why she gets a figure of a minute and a half for the building to collapse?!

That's pretty much what I thought she'd done (good to have it confirmed). What would happen if she used the same train of thought on any demolition or building collapse? What I'm trying to get at, is that if her theory were true, wouldn't she effectively be showing that no building can collapse at a fast speed, irrespective of whether it's been intentionally demolished or collapsed as a result of a natural disaster?

[delphi_ote]

That's pretty much what I thought she'd done (good to have it confirmed). What would happen if she used the same train of thought on any demolition or building collapse? What I'm trying to get at, is that if her theory were true, wouldn't she effectively be showing that no building can collapse at a fast speed, irrespective of whether it's been intentionally demolished or collapsed as a result of a natural disaster?
Basically, yes. And this woman teaches college courses. In engineering. :(

[Mashuna]

Basically, yes. And this woman teaches college courses. In engineering. :(

Well, if she teaches college courses, that proves the collapse must have been due to the Death Star. Or something.

I've only made brief forays into the CT area, as I find the whole place just too depressing. I've read about Judy Woods being one of the star performers for the MIHOP crowd, but if this is the level it's operating on, I think I'll withdraw again, maybe come back when people can generally accept that the reason for the collapse of the towers was two great big aeroplanes flying into them. :(

[fuelair]

Where does her initial velocity of 0 come from for boith objects? If one of them is not moving, there isn't a collision (and 0 is correct) but one being 0 and the other moving does not give a 0 answer. And of course, the tower as a whole certainly moved to a very small extent in the direction the plain was moving (but definitly less than a replacement of actual mass for the m she speaks of would indicate as much of the momentum went into individual collisions of rather small particles as the plane shredded/powderes as did parts of the building. She seems a very stupid or very physics illiterate person (I'm making an assumption on that last word.)

[TruthSeeker1234]

I agree Dr. Wood doesn't always express her ideas clearly. But here is what she is getting at with the billiard ball example, I think.

Consider two balls of equal mass. Ball A is moving and ball B is at rest. A hits B. In a perfect collision, A gives all its energy to B. B begins moving at the same velocity that A was moving, but A stops moving.

This should hold true in a vertical fall. Floor A falls and hits floor B. B begins moving at the speed A was moving prior to the impact, but A must stop, and begin falling all over again. Some part of the falling mass must stop at each impact.

The situation in real life is more complicated of course. We don't have equal masses. We don't have perfect collisions. But the point she makes applies. If momentum is transferred from one object to the other, we must not forget to subtract that momentum from the first object.

[R.Mackey]

I agree Dr. Wood doesn't always express her ideas clearly. But here is what she is getting at with the billiard ball example, I think.

Consider two balls of equal mass. Ball A is moving and ball B is at rest. A hits B. In a perfect collision, A gives all its energy to B. B begins moving at the same velocity that A was moving, but A stops moving.

This should hold true in a vertical fall. Floor A falls and hits floor B. B begins moving at the speed A was moving prior to the impact, but A must stop, and begin falling all over again. Some part of the falling mass must stop at each impact.
No, that's not what she's getting at. She's simply, completely, utterly, stupidly wrong.

The situation in real life is that masses A and B remain in contact after collision. The total momentum afterwards is the same as before.

Mass A does not stop, but only slows down. Mass B is accelerated -- in a very short period of time -- to the same speed as Mass A now has.

NO part of the falling mass must stop at each impact. It simply is not true. To take that argument, if I go shoot at bowling pins with my .22 rifle, when I hit the pins, the pin would topple over, and the bullet would screech to a halt and drop right there on the ground in front of the pin.

Madness!

The situation in real life is more complicated of course. We don't have equal masses. We don't have perfect collisions. But the point she makes applies. If momentum is transferred from one object to the other, we must not forget to subtract that momentum from the first object.
Nobody has forgotten. Once again, go take a look at Greening's (http://www.911myths.com/WTCREPORT.pdf) paper. He doesn't forget.

[TruthSeeker1234]

Greening: We now apply this simple model to the WTC collapse. We assume that both
WTC building collapses began with an upper block of nfloors collapsing onto a series of
lower floors as in the “domino effect”. Thus, Greening, and JREF's, imagine this:
http://i18.photobucket.com/albums/b108/janedoe444/present/ModelA.jpg

How can we take this seriously when it so obviously disagrees with observed reality?

Wood, on the other hand, assumes material is getting pulverized into powder. This matches reality.

How do I size the picture smaller?

[Garb]

Greening: Thus, Greening, and JREF's, imagine this:
http://i18.photobucket.com/albums/b108/janedoe444/present/ModelA.jpg

How can we take this seriously when it so obviously disagrees with observed reality?

Wood, on the other hand, assumes material is getting pulverized into powder. This matches reality.

How do I size the picture smaller?

Worst. Diagram. Ever.

[Anti-sophist]

I still can not get over the utter stupidity of the very first comment in that math.

She, literally says, "Newton's first law shows that pulverization is impossible." That is a literal math-> english translation of her argument. No explaination. Not analysis... just... that stupid statement, in mathematical form.

I can't figure out what she even is getting at. It's like a little stupid seed in my head slowly sprouting and growing stupid flowers.

[einsteen]

That's indeed the same as saying that your Maxwell equations imply that I can not destroy my radio... The only thing I agree with is that the pulverization starts at an early stage, if you put your coordinate origin very high the massive pulverization starts after the initial crash already, how does it effect the momentum, maybe I'm wrong and it doesn't matter, but it should at least be a factor to take into account

[beachnut]

I agree Dr. Wood doesn't always express her ideas clearly. But here is what she is getting at with the billiard ball example, I think.

Consider two balls of equal mass. Ball A is moving and ball B is at rest. A hits B. In a perfect collision, A gives all its energy to B. B begins moving at the same velocity that A was moving, but A stops moving.

This should hold true in a vertical fall. Floor A falls and hits floor B. B begins moving at the speed A was moving prior to the impact, but A must stop, and begin falling all over again. Some part of the falling mass must stop at each impact.

The situation in real life is more complicated of course. We don't have equal masses. We don't have perfect collisions. But the point she makes applies. If momentum is transferred from one object to the other, we must not forget to subtract that momentum from the first object.

you fell for a real nut case, Judy Wood, and you are now thinking she has something.

This is in the vertical, and these are not balls. She messed up her momentum and model of the WTC. She is proved wrong by what happen on 9/11. Until you show up with some evidence her model is junk, as are her calculation and lack of calculations.

Gravity is ignored by woods except for her cute, stop and go version of balls.

Are you Judy?

Cause the only person who could think her balls have any merit is her!

You like her beam weapon too.

You need to get an education. (did your parents us the term "pull it"? as they took away your college funds.)

[delphi_ote]

Wood, on the other hand, assumes material is getting pulverized into powder. This matches reality.
Now this I have to see. TruthSeeker "interpreting" Wood. Botched physics viewed through the looking glass twice.

[Gravy]

But the point she makes applies.
:notm


The point she makes – her whole point – is that the tower collapses should have taken over a minute and a half and could not have happened as observed due to gravity.

Now she posits that gravity's job may have been aided by a Star Wars energy beam.

Why are you CTs so afraid to say "this person is batcrap crazy, this analysis has always been laughably, horribly wrong, and we need to point that out because it's making our "movement" look ridiculous?"

[beachnut]

Judy Wood is batcrap crazy.

Yes I second that motion. I accept that statement fully and need no math proof! I approve this statement.

[twinstead]

Why are you CTs so afraid to say "this person is batcrap crazy, this analysis has always been laughably, horribly wrong, and we need to point that out because it's making our "movement" look ridiculous?"

Jesus, Gravy, if they did that in every instance they would be forced to admit that every member of their movement makes them look ridiculous.

[Mobyseven]

Consider two balls of equal mass. Ball A is moving and ball B is at rest. A hits B. In a perfect collision, A gives all its energy to B. B begins moving at the same velocity that A was moving, but A stops moving.

This should hold true in a vertical fall. Floor A falls and hits floor B. B begins moving at the speed A was moving prior to the impact, but A must stop, and begin falling all over again. Some part of the falling mass must stop at each impact.

Have you tried the above billiard ball experiment on a vertical billiard table? I know that sounds silly, but I think you might just discover something if you try it...

May I suggest you name whatever peculiar force you discover 'gravity'. I dunno why, but it just has a sort of ring to it...

[delphi_ote]

Have you tried the above billiard ball experiment on a vertical billiard table? I know that sounds silly, but I think you might just discover something if you try it...

May I suggest you name whatever peculiar force you discover 'gravity'. I dunno why, but it just has a sort of ring to it...
:jrefwelcome
I like you already. :D

[Anti-sophist]

That's not really fair. Truthseeker's explaination is actually technically correct (that is to say, the explaination of the model is correct... the correctness of the model, on the other hand..)

If we think of a tube of equally space billard balls, vertically, and we assume that every ball is at rest by some magical force until it is contacted. Then when we drop a ball down the tube, it will hit the first ball, transfer all of it's momentum, momentarily come to rest, and then begin free-falling.

The net effect is every ball will follow the same path. It will get hit from above, inheret that speed, accelerate downwards, hit the ball below, come to a complete stop, and then enter freefall.

The net effect of this is that the "collapse wave" will proceed at freefall speed. The first ball will accelerate one floor, and transfer that velocity to the next ball who will fall at freefall acceleration, etc, etc. The "collapse wave", then, proceeds at freefall.

It's well established that the collapse doesn't proceed at freefall, so why is our model making an incorrect prediction? As has been pointed out, repeatedly, the collapse isn't elastic. An elastic model is fundamentally flawed. As has been repeatedly shown, a perfectly inelastic model of collapse is far more accurate and produces much better predictions.

I'm actually thankful for truthseeker for explaining this billiard ball model to me. The concept actually makes enough sense to be wrong. That is one step above Judy's "Newton's First Law implies pulverization is impossible". This statement makes so little sense that it brings to mind Everyones Favorite Wolfgang Pauli Quote (EFWPQ, if you will).

[fuelair]

Judi may have wood, but she don't have math.

[Spins]

Have you tried the above billiard ball experiment on a vertical billiard table? I know that sounds silly, but I think you might just discover something if you try it...

May I suggest you name whatever peculiar force you discover 'gravity'. I dunno why, but it just has a sort of ring to it...
Can you imagine if Sir Isaac Newton got hit on the top of the head by a billiard ball instead of an apple!

With the brain injury he would have no doubt sustained he would have never discovered universal gravitation and the three laws of motion!

Instead of the event being called "Newton's Apple" it would have been called "Newton's Billiard Ball".

:D

[Mojo]

And her "model" of the collapse is so unrealistic it's absurd. Basically, the floors colliding with each other completely stop the entire collapsing mass.This is a bit like like the fallacy involving an eastbound freight train hitting a westbound fly, where because the fly was originally going West but ends up going East it must at some point have been stationary, and as this must have happened when the fly was in contact with the freight train, the fly must have stopped the train!

[Horatius]

Greening: Thus, Greening, and JREF's, imagine this:
http://i18.photobucket.com/albums/b108/janedoe444/present/ModelA.jpg

How can we take this seriously when it so obviously disagrees with observed reality?

Greening:

We now apply this simple model to the WTC collapse. We assume that both WTC building collapses began with an upper block of nfloors collapsing onto a series of lower floors as in the “domino effect”.

So, out of curiosity, do you know what a physicist means when he refers to a "simple model"? Hint: They don't expect it to correspond to reality 100%.

[ktesibios]

The thing is, even if we accept the notion that an elastic collision a' la pool balls or one of those doodads with the five steel dingleberries suspended from a frame (another example Woods uses) is an adequate analogy, her contention that the falling mass (the cue ball) should stop upon hitting the floor below (the object ball) still doesn't work.

If m1 is the mass of the "cue ball", m2 is the mass of the "object ball" and v1 and v2 are their respective velocities before the collision and v'1 and v'2 are their velocities after the collision, then the velocity of the "cue ball" after the collision is given by:

v'1=(v1(m1-m2)+2m2v2)/(m1+m2)

Okay, so if v'1 is 0, then (v1(m1-m2)+2m2v2) must be equal to 0. If v2 is 0 (the "object ball" isn't moving before the "cue ball" hits it), then 2m2v2=0, so v1(m1-m2) must equal 0. If v1 is not equal to 0 (the "cue ball" is moving before it hits the "object ball", then the only way that v'1 will come out to 0 is if m1-m2=0.

This is the case for a pool game or one of the doodads with the five steel dingleberries, but in the case of the WTC towers, m1 (the mass of the falling upper block) is obviously considerably greater than m2 (the mass of the floor it lands on).

Taking that first equation, setting v'1 to 0 and solving for v2, I get:

v2=-(v1(m1-m2))/2m2

If m1>m2 then v2 is nonzero and negative, i.e. the "object ball" must be moving towards the "cue ball" before the collision.

Even if the WTC had been built out of pool balls, for what Woods claims should have happened to happen, each floor would have had to leap upwards just before the falling mass hit it.

How you do that? Anti-gravity beams?

[Spins]

How you do that? Anti-gravity beams?
:eek:

In her mind that would be a plausible explanation, they don't call her Judy "Beam Weapon" Wood's for nothing you know!

[Chris Haynes]

Basically, yes. And this woman teaches college courses. In engineering. :(

Not any more it seems. I noticed on an earlier thread when I tried to link to her Clemson webpage and it was gone. I checked their directory and she is missing: http://www.ces.clemson.edu/main/directory.pdf

A search at http://www.clemson.edu/phonebook/ also brought up nothing.

[JamesB]

Not any more it seems. I noticed on an earlier thread when I tried to link to her Clemson webpage and it was gone. I checked their directory and she is missing: http://www.ces.clemson.edu/main/directory.pdf

A search at http://www.clemson.edu/phonebook/ also brought up nothing.

She was an associate professor, and was not picked up for tenure this year. Apparently Clemson prefers to employ engineering professors who actually know something about engineering.

[Spins]

Not any more it seems. I noticed on an earlier thread when I tried to link to her Clemson webpage and it was gone. I checked their directory and she is missing: http://www.ces.clemson.edu/main/directory.pdf

A search at http://www.clemson.edu/phonebook/ also brought up nothing.
Yes you are right she doesn't teach there anymore...

Judy Wood, until recently an assistant professor of mechanical engineering at Clemson University, has been cited by conspiracy theorists for her arguments the buildings could not have collapsed as quickly as they did unless explosives were used.

http://www.newsmax.com/archives/articles/2006/8/6/195730.shtml

[Anti-sophist]

This is the case for a pool game or one of the doodads with the five steel dingleberries, but in the case of the WTC towers, m1 (the mass of the falling upper block) is obviously considerably greater than m2 (the mass of the floor it lands on).


This is where you make your "mistake". In her model of collapse, each floor is falling independantly, thus each collision is between equal masses. It's ridiculous, I know. I'm tempted to make a MATLAB simulation of her model of the collapse because it would make a pretty picture.

[delphi_ote]

Not any more it seems. I noticed on an earlier thread when I tried to link to her Clemson webpage and it was gone. I checked their directory and she is missing: http://www.ces.clemson.edu/main/directory.pdf

A search at http://www.clemson.edu/phonebook/ also brought up nothing.
Woa... maybe my e-mail actually had some impact.

[maccy]

She was an associate professor, and was not picked up for tenure this year. Apparently Clemson prefers to employ engineering professors who actually know something about engineering.

Her students didn't think much of her either:

http://www.ratemyprofessors.com/ShowRatings.jsp?tid=495285

[Kent1]

:notm


The point she makes – her whole point – is that the tower collapses should have taken over a minute and a half and could not have happened as observed due to gravity.

Now she posits that gravity's job may have been aided by a Star Wars energy beam.

Why are you CTs so afraid to say "this person is batcrap crazy, this analysis has always been laughably, horribly wrong, and we need to point that out because it's making our "movement" look ridiculous?"
You said the C-word! They're afraid of it because they might have to revaluate their own sanity.

[ellindsey]

Here is a very simple Python script I put together to model the fall with inelastic collisions. This script treats each floor as an independant object and assumes all floors are equal mass. It assumes all collisions are perfectly inelastic, and that the mass of each floor is added to the mass of the falling debris block. I did put in a term to simulate some mass being lost to the sides with each floor.

This script does not factor in deceleration due to the energy it would take to overcome the structure of the building. I'm not sure how to best add that. I don't claim that this script is particuarily accurate, but I do believe it to be a much more accurate calculation than Judy Wood's.

With the assumptions made in the code, I get a total collapse time of 15.7 seconds, which does appear to be close to what we see on the videos.


from math import *

floors = 110.0 #110 stories
impactfloor = 95.0 #collapse initiation floor
floordist = 12.4 #in feet, 1,368 feet divided by 110 floors
gravity = 32.0 #feet per second squared
floormass = 1.0 #assume all floors have the same mass
massloss = 0.05 #amount of mass to fall off to sides on each impact

time = 0.0 #total accumulated collapse time
height = impactfloor * floordist #height of collapse wave
debrismass = (floors - impactfloor) * floormass #mass of debris falling
v = 0.0 #velocity of debris falling

while height > 0:
#Freefall one floor:

t = (-v + sqrt(v*v + 2.0 * gravity * floordist)) / gravity
height = height - floordist
time = time + t
v = v + gravity * t

#impact next floor
#Assume perfectly inelastic collision
#Does not factor in energy to break floor

v = (v * debrismass) / (debrismass + floormass)
debrismass = (debrismass + floormass) * (1 - massloss)

print time, "seconds"

[maccy]

There's an interesting discussion about Judy Wood and her theories by students and alumni (at first, at leadt) of her former Univeristy at the Clemson Talk forums here: http://www.clemsontalk.com/vb/showthread.php?t=22999

The main debunker ("Jeff the Great") actually works for NIST.

I'm pretty sure that Truthseeker1234 turns up as "Brian" on page 3 - with predictable results.

[beachnut]

The article also cites former assistant professor of mechanical engineering Judy Wood. Until just recently, she was employed by Clemson, always thought to be an institution of higher learning as opposed to a government propaganda center. Wood is quoted and says it all: "'If the U.S. government is lying about how the buildings came down, anything else they say cannot be believed. So why would they want to tell us an incorrect story if they weren't part of it?'"

The article continues: "At Clemson, Wood did not receive tenure last year, but her former department chair, Imtiaz ul Haque, denies her accusation that it was partly because of her September 11 views. 'Are you blackballed for delving into this topic?' Oh yes,' Wood said. 'And that is why there are so few who do. Most contracts have something to do with some government research lab. So what would that do to you? The consequences are too great for a career. But I made the choice that the truth was more important.'"


Truth movement experts have no ability to understand their lack of performance in the real world.

It becomes a CT as they loose their jobs because they are nut cases; translation = shown the same great abilities in their jobs as they do in their outstanding research on how beam weapons destroyed the WTC.

If Judy's web site is indicative of her abilities in the class room or her understanding of real science and research. There is no doubt why she will not have a job teaching at Clemson.

[maccy]

Truth movement experts have no ability to understand their lack of performance in the real world.

It becomes a CT as they loose their jobs because they are nut cases; translation = shown the same great abilities in their jobs as they do in their outstanding research on how beam weapons destroyed the WTC.

If Judy's web site is indicative of her abilities in the class room or her understanding of real science and research. There is no doubt why she will not have a job teaching at Clemson.

From a former student at Clemson, who now works for NIST:

On a personal note, Judy Wood was arguably the dumbest person I've ever met, and by far the most incompetant instructor Clemson has ever hired. My friends in her Statics class learned nothing. She was a terrible lecturer, had no grasp of the concepts involved, was disorganized, unpleasent both inside and outside of class and completely failed to produce any meaningful research while at Clemson.

http://www.clemsontalk.com/vb/showpost.php?p=531540&postcount=2

[uk_dave]

I'm pretty sure that Truthseeker1234 turns up as "Brian" on page 3 - with predictable results.

Yeah...he even references himself on page 6 lol

[beachnut]

now I can send my money to CU

I was afraid they had no acedemic standards anymore when Judy showed up teaching

[beachnut]

if only CU had taught me how to speel

[uk_dave]

oooooooo they have some goodies posting on that site

I loved the way they destroyed 'brians' claims about the station location....but sad that such blatant lying on the part of the 'truth' movement can be brushed aside so easily as if it is somehow acceptable.

If someone had fed me such incorrect information and allowed me to make a fool of myself when using it in a debate, I wouldn't trust the 'pushers' data on anything else.

A bit like Loose change, in fact.......lol

[maccy]

I've just posted on the thread to let them know about the beam weapons theory and to invite them over here.

[Crungy]

Yeah...he even references himself on page 6 lol


Yes, I immediately caught that one too.

MissG reminds me of a certain JREFer....

[uk_dave]

MissG is judy wood's pal...they go to conferences together and everything.

Though to begin with, of course, she tried to pass herself off as an impartial source for the hearsay claim that the nist guy had shocked the assembled engineers with his offhand comments about symmetrical collapse.

this is fun!
:D

[uk_dave]

Nice invite maccy........ now we must ask truthseeker about those subway pictures...... muhahahahahaha

[uk_dave]

I do hope that jeff takes you up on the invite.... having someone from NIST posting on here will do wonders for our credibility with the 'troofers'...ermmmmm...ummmmmm ....wellllll maybe not....but who cares?

[Minadin]

From Maccy's link - http://www.clemsontalk.com/vb/showpo...40&postcount=2 (http://www.clemsontalk.com/vb/showpost.php?p=531540&postcount=2)


As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1 It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.
That was probably one of the best arguments I have heard in a while.

[ktesibios]

This is where you make your "mistake". In her model of collapse, each floor is falling independantly, thus each collision is between equal masses. It's ridiculous, I know. I'm tempted to make a MATLAB simulation of her model of the collapse because it would make a pretty picture.

Ahh, now I get it. For her model to work, all that's necessary is for me not to notice that the top pool ball is actually a bowling ball. ;)

This is cool! It means my project to create an h-parameter model of a cauliflower isn't hopeless! :D

BTW, do they still make those doodads with the steel dingleberries? They were fun- if you lifted a ball at each end and released them with the right time offset, you could get some pretty def beats going.

[maccy]

From Maccy's link - http://www.clemsontalk.com/vb/showpost.php?p=531549&postcount=4 (http://www.clemsontalk.com/vb/showpost.php?p=531540&postcount=2)

That was probably one of the best arguments I have heard in a while.

I've fixed the link so it points to the post you got the quote from. It actually comes from this report here:

http://www.tms.org/pubs/journals/JOM/0112/Eagar/Eagar-0112.html

which was published in December 2001, and so doesn't have access to the data in the NIST report.

[The Almond]

Howdy! I was introduced to this site when some of your members came over to Clemson Talk and noticed our, rather scaled down, version of 9/11 conspiracy debunking. Between us, we were curious if anyone would notice us, given the renewed interest in conspiracy theories heralded by the Loose Change documentary.

Maccy mentioned that it would provide a much needed credibility boost if one of the students, a NIST employee, were to begin participating in the forums. However, to paraphrase Carl Sagan, in science, there are no experts. Indeed, it doesn’t take a genius to read the NIST NCSTAR 1 report. It is, after all, written in language for the laity, relegating the rigorous mathematical proof and referencing to the appendices. It also doesn’t take a NIST scientist to know that conspiracy theories are garbage. All people who use valid scientific and logical reasoning are entitled to equal regard as “experts.”

Were I to assign any type of motivation to the student, I would say it’s probably more personal than philosophical. If the people you worked with, respected, admired and emulated were being blanketed by accusations of deceit, their arguments dissembled into various straw man arguments, and their work called a conspiracy, you’d be angry, too. It would infuriate you that hundreds of thousands of man-hours of research could be so casually dismissed as a fabrication, as though NIST employees toss their degrees, education and professional reputations to the wind in favor of a thesis they’ve been told to prove without proof. Inherent to all claims of conspiracy is the claim that these researchers are liars and fabricators of evidence. Dylan Avery and his cronies should be ashamed. They make broad accusations against the government from coercion to money laundering to fabrication, and all are made without direct proof.

Anyway, I’m at least interested in seeing what you folks have to say. It seems like you run a pretty tight ship here with logical, mathematical and scientific analyses in your posts. I’m eager to contribute.

[twinstead]

Welcome abord Almond

[maccy]

Welcome!

I do feel that I need to clarify one thing from your post:


Maccy mentioned that it would provide a much needed credibility boost if one of the students, a NIST employee, were to begin participating in the forums.

What I actually said was:

Jeff the Great's expertise and NIST experience would be greatly appreciated if he feels like dropping by.

http://www.clemsontalk.com/vb/showpost.php?p=545011&postcount=213

I don't think this forum requires "a much needed credibility boost" - I'm sure as you look around you'll agree - and it wasn't my intention to give that impression. I thought that "Jeff the Great" would add to the forum partly because of his expertise as an engineer (which I took to contributing to the quality of his posts on your board) and also because his experience in working for NIST would give an interesting perspective on the evidence. The evidence is at heart all that matters - but perspective and good communication can help to get it across.

Once again, though, welcome to the forum!

[The Almond]

Here is a very simple Python script I put together to model the fall with inelastic collisions. This script treats each floor as an independant object and assumes all floors are equal mass. It assumes all collisions are perfectly inelastic, and that the mass of each floor is added to the mass of the falling debris block. I did put in a term to simulate some mass being lost to the sides with each floor.

Very impressive Mr. Ellindsey. I applaud your ingenuity in code.

This script does not factor in deceleration due to the energy it would take to overcome the structure of the building. I'm not sure how to best add that.

You shouldn't have to. NIST does not support the "pancake theory" as a means for destroying the support for each floor. See question 2 on the NIST FAQ.

I don't claim that this script is particuarily accurate, but I do believe it to be a much more accurate calculation than Judy Wood's.

By accounting, at least in some part, for the momentum reactions at each floor, you've done far more than she has. Billiard balls = reinforced concrete flooring? I don't think so.

With the assumptions made in the code, I get a total collapse time of 15.7 seconds, which does appear to be close to what we see on the videos.

This part particularly impressed me. The NIST report notes that parts of the interior columns and the core of the building are known to have stood 15 to 25 seconds after collapse initiation.

I don't know if it's been mentioned here, but the commonly reported time of "about 9 seconds" is that reported for the first exterior columns to strike the ground and create a significant seismic incident. The NIST report makes no mention of where the panels came from, or whether or not they were part of the core of the building. It is far more likely that the first panels to strike the ground were part of the ejecta of the building, which fell through the air, unobstructed. Despite video evidence supposedly showing the contrary, the collapse of the WTC towers was not a simple, neat little mess. It was an incredibly complicated bit of work which was largely obstructed by dust and not widely reported by the people the building fell on.

Judy Wood's assumptions and objections stem entirely from the straw man argument that NIST asserts that the collapse happened entirely in 9 seconds. It doesn't and NIST notes that. See sections 5 and 6 of the NIST FAQ I posted above.

[WildCat]

By accounting, at least in some part, for the momentum reactions at each floor, you've done far more than she has. Billiard balls = reinforced concrete flooring? I don't think so.
Actually the concrete floors were lightweight, and not reinforced.

[The Almond]

I don't think this forum requires "a much needed credibility boost" - I'm sure as you look around you'll agree - and it wasn't my intention to give that impression.

I agree, you clearly did not mean to imply this. I apologize for the misunderstanding and for my poor choice of words.

I thought that "Jeff the Great" would add to the forum partly because of his expertise as an engineer (which I took to contributing to the quality of his posts on your board) and also because his experience in working for NIST would give an interesting perspective on the evidence.

This is rather unfortunate. Federal government employees are specifically barred from using their positions in any official capacity. Unless they're in a public relations job, they cannot comment publicly on the validity or naure of any research they are not directly involved with. This is pretty much the same in industry, though industry seems more tight lipped these days.

I agree that a NIST employee would provide an excellent viewpoint, but only if he or she were directly related to the research.

The evidence is at heart all that matters - but perspective and good communication can help to get it across.


Well said.

[The Almond]

Actually the concrete floors were lightweight, and not reinforced.

From NCSTAR 1, section 5.7, page 75:
Two types of concrete were used for the floors of the WTC towers: lightweight concrete in the tenant office areas and normal weight concrete in the core area.

I acknowledge your point that the floors were not reinforced. Technically they were composite floors as the steel was not imbedded in the concrete. Thanks for pointing this out.

[Arkan_Wolfshade]

I do hope that jeff takes you up on the invite.... having someone from NIST posting on here will do wonders for our credibility with the 'troofers'...ermmmmm...ummmmmm ....wellllll maybe not....but who cares?

To hezmana with the truthers; I'd just love the chance to chat with somebody that was part of the investigative team and to get there input on the analyses we've done here. That would be teh r0xx0rz!

[Minadin]

It is pretty cool to have a guy from the NIST posting here, welcome to the forum, Jeff the Great / Almond. I look forward to putting your structural jargon into layman's terms while you correct me on the various technical details of how the structure actually works. (Isn't that what architects and engineers usually do?)

[Trigood]

Here's something from that ClemsonTalk thread:

Bush was warned about Al Queida and didn't want to be bothered....

... Learn to spell Al Queda correctly and then we can continue this conversation.
All right dudes!!!

:clap: :clap: :clap: :clap: :clap:

[Trigood]

I noticed that soon after "Brian" appeared, Harksaw asked him something I've been itching to ask Ace as well:

Have you ever taken a physics class?

[Bronze Dog]

Weclome aboard, The Almond. You ain't no nut!

[The Almond]

It is pretty cool to have a guy from the NIST posting here, welcome to the forum, Jeff the Great / Almond. I look forward to putting your structural jargon into layman's terms while you correct me on the various technical details of how the structure actually works. (Isn't that what architects and engineers usually do?)

Thanks for your kind welcome. Just to be clear though, I don't work at NIST, nor do I represent the researchers (government or independent) who produced the WTC reports. I'm just a graduate student in civil engineering at Clemson with a pretty solid background in structural engineering and materials science. I have read the entirety of the NIST and FEMA reports, though, and I'm more than happy to provide references to both when making claims and corrections.

[Gravy]

Here's something from that ClemsonTalk thread:

All right dudes!!!

:clap: :clap: :clap: :clap: :clap:Er, sorry, but I've never seen either of those spellings.

[T.A.M.]

The Almond:

Welcome to the JREF Forum on Consipracy Theories. I truely enjoyed watching you tear Brian (sock puppet for TS1234 here) and Jack Straw new a&*holes. your work over here is more than welcome.

Look forward to your input/contributions to this site, where you find no end to a number of things:

(1) Interesting, and often very aggressive debate
(2) Insane theories (courtesy of some of our less than sane CTers)
(3) References to ALOT of useful information. In particular, a frequent user named "Gravy" has collected a vast wealth of info related to all aspects of 9/11.

If you ever get annoyed with the inability of the CTers to see the logic in things, just remember, for every CTer you will never convince, there are 50 lurkers that you will (we have almost as many lurkers as we do members on a given day.

TAM (The Artistic Macrophage)

Edit: I am going with Al-Qaeda:)

[Minadin]

Ah, my mistake, Almond, I must have received a wrong impression of a false assumption, thanks for setting me straight, and welcome aboard in any event.

[ellindsey]

I've updated my script with some numbers from the latest Greening paper. The current version factors in the energy required to destroy each floor (which includes the energy required for the observed pulverization of each floor).

With the numbers and assumptions I've plugged in, the script gives a collapse time of 19.2 seconds, which is still reasonably close to the observed collapse times. I have found that the collapse time is highly sensitive to how much mass we assume was lost from the collapse wave at each stack. The Greening paper states that at least 90% of the mass was retained in each collision, and that's the number I've plugged into the code at the moment. Feel free to copy this script and plug your own numbers in.

I don't claim that this is a particuarily accurate simulation of the actual collapses, merely a tool for visualizing how a progressive collapse occurs and estimating the time required.

from math import *

floors = 110.0 #110 stories
impactfloor = 95.0 #collapse initiation floor
floordist = 3.7 #in meters
gravity = 9.8 #meters per second squared
floormass = 3860000.0 #in kg, assume all floors have the same mass
massloss = 0.1 #amount of mass to fall off to sides on each impact
crushenergy = 603000000.0 #603MJ to destroy one floor

time = 0.0 #total accumulated collapse time
height = impactfloor * floordist #height of collapse wave
debrismass = (floors - impactfloor) * floormass #mass of debris falling
v = 0.0 #velocity of debris falling

while height > floordist and (v > 0.0 or time == 0.0):
#Freefall one floor

t = (-v + sqrt(v*v + 2.0 * gravity * floordist)) / gravity
height = height - floordist
time = time + t
v = v + gravity * t

#impact next floor

#calculate impact energy, 1/2MV^2
e = 0.5 * debrismass * v * v
#subtract energy required to destroy floor
e = e - crushenergy
if e < 0: #collapse stalled, not enough energy to break floor!
v = 0;
else:
#accumulate mass of next floor
debrismass = debrismass + floormass
#calculate resulting velocity
v = sqrt((2 * e) / debrismass)
#and spill some off the sides
debrismass = debrismass * (1 - massloss)

if v > 0.0:
print "Collapse reached ground at",time,"seconds"
else:
print "Collapse halted at",height,"meters after",time,"seconds"

[R.Mackey]

I've updated my script with some numbers from the latest Greening paper. The current version factors in the energy required to destroy each floor (which includes the energy required for the observed pulverization of each floor).

With the numbers and assumptions I've plugged in, the script gives a collapse time of 19.2 seconds, which is still reasonably close to the observed collapse times. I have found that the collapse time is highly sensitive to how much mass we assume was lost from the collapse wave at each stack. The Greening paper states that at least 90% of the mass was retained in each collision, and that's the number I've plugged into the code at the moment. Feel free to copy this script and plug your own numbers in.

I don't claim that this is a particuarily accurate simulation of the actual collapses, merely a tool for visualizing how a progressive collapse occurs and estimating the time required.

Welcome, ellindsey. Nice model. It's good to see that even something so simple can get pretty close to the real thing.

If you want to add some detail to the model and perform a more detailed sensitivity analysis, here are a couple of other things you might try:

1. While overall collapse time is sensitive to the lost mass fraction, I suspect it's even more sensitive to lost mass at the initiation of collapse versus later in the sequence. Since the upper block is relatively undamaged at the start, mass retention can be assumed to be 100% for the first five or ten floors.

(Also, as I've argued repeatedly, "lost mass" isn't truly lost because in order for it to fall anything but vertically, it has to come in contact with the structure. The NIST "progressive collapse" postulates that the heavy steel elements remained tied by the sagging floors until secondary damage destroyed those connections completely; most loss over the sides is the facade and lighter office / interior materials squeezed out by the collapse.)

2. Your energy to destroy a floor is also constant. In reality higher floors will be easier to destroy due to lighter construction. Again, the total collapse time should be more sensitive to variation in the upper floors. You might try a floor energy function that is linear with respect to floor number and see what happens.

(Also, don't forget the first 10 floors or so were heavily damaged and weakened by the fires. This will also shave time off the real case that isn't represented here.)

[einsteen]

I'm working on the exact calculation (in very small steps), I got it for the end speed (about 51.8 m/s) but the time is a little bit tricky, it involves harmonic functions, the sum of squares can be calculated exactly.

I'm wondering what the mass distribution was of the building and the energy to break a floor. In the collapse the factor E_floor_break/m_floor is very important.

[T.A.M.]

http://forums.randi.org/imagehosting/thum_10761455202155aceb.jpg (http://forums.randi.org/vbimghost.php?do=displayimg&imgid=2493)

The above is where my line of thinking is. If you look at it, there are 3 possible Free Fall times, depending on the height (d) you use in the equation...

d = 0.5*g*t*t

to give

t = square root of (d/5)

if you use top of building, free fall is = 9.13s
if you use the 98th floor, free fall is = 8.62 s
if you use the 104th floor (assumed center of gravity of top portion),
then free fall is = 8.88s

Seems like a small difference, but in fact it is aabout 1/2 a second difference, which out of 8-9 seconds is significant.

Once again, any help would be appreciated.

TAM


**The above is a duplicate of the one I posted on Loose Change thread, but I got no response. It refers to my speculation over what falling distance that NIST and others use to calculate the theoretical "Free Fall time" it would take the for the towers to fall, in free fall. Please, if anyone can help a guy with this, I am all ears.

TAM