Letters from Green Island

Feb 4 08

In Which an OCT (Official Conspiracy Theory) wannabe witch doctor gets a lesson from On Green Island

(if you just want to get to the interesting part (my response to the same-old-same-old OCT) just click here - I took the time to do this page because I think there are at least a couple of new things in my 'rebuttal' (quotation marks because rebuttals are usually used for serious things, but there's little really serious about the OCT voodoo-doodoo, sort of like 'seriously' responding to a flat-earther or jehovah's witness or something equally behind the looking glass) that have not really been pointed out before in showing how nonsensical the OCT is....)

On an email list, I received this (Feb 4/08):

We're having a big argument on one of my lists about the collapse of the WTC towers, where I'm a sceptic as they don't make sense and there's overwhelming evidence against the official version. A believer put this one on the list, trying to prove the official claims

In my opinion, if the collapse had been "natural", the inner core of some 47 large steel girders should have been left standing, at least for some time, before toppling over, as they've formed a kind of tube, very difficult to impossible to collapse vertically. There was no toppling over , both towers fell down in about 7 seconds and the third one, Building 7 wasn't even hit before it went down and the vertical girders broke into small pieces, which makes absolutely no sense.

What do our scientists think about the math in this article ?

Cheers ....

I found the article below at http://www.burtonsys.com/staticvdyn/ It is written by a Dave Burton.

As you will see, it explains, in some detail, why the towers collapsed at nearly free fall speed without being assisted by explosives. The URL also has pictures which illustrates some of his points
E2....

Static v. Dynamic Loading: Why the WTC Towers Fell So Fast

Some conspiracy theorists are puzzled about why the WTC towers fell at almost free-fall speed on Sept. 11, 2001. They suppose that the speed of collapse is evidence that something or someone must have destroyed the structural integrity of the undamaged lower part of each tower.

After all, they reason, "only the upper floors of the building were damaged, so why did the lower floors collapse, and why did they fall so fast?"

This web page answers those questions, simply enough for even a conspiracy theorist to comprehend (I hope). I do use some simple math and some very basic physics, but even if you don't understand that part you should still be able to comprehend the basic reasons that the towers fell so fast.

What the conspiracy theorists apparently don't understand is the difference between static and dynamic loading. ("Static" means "while at rest," "dynamic" means "while moving.")

If you don't think it can make a difference, consider the effect of a stationary bullet resting on your chest, compared to the effect of a moving bullet striking your chest. The stationary bullet exerts a static load on your chest. A moving bullet exerts a dynamic load.

As a more pertinent example, consider a 110 story building with a roof 1,368 feet high (like the WTC Twin Towers). Each floor is 1368/110 = 12.44 feet high, or approximately 3.8 meters.

Now, suppose that the structural steel on the 80th floor collapses. (Note: I'm using as an example 2 WTC, which was the building that collapsed first.)

The collapse of the 80th floor drops all the floors above (which, together, are equivalent to a 30 story building!) onto the 79th floor, from a height of approximately 12 feet.

Of course, the structure of the lower 79 floors has been holding up the weight of the top 31 floors for many years. (That's the static load.) So should you expect it to be able to hold that same weight, dropped on it from a height of 12 feet (the dynamic load)?

The answer is, absolutely not!

Here's why.

First, let's calculate approximately how fast the upper 30 floors slammed into the 79th floor. (If you slept through high school physics, you may want to skip ahead to the result.) d=distance, g=acceleration of gravity, t=time, v=velocity
d = 0.5 g x tē
Solving for t:
2d = g x tē
tē = 2d / g
t = sqrt(2d/g)
t = sqrt(2d) / sqrt(g)

v = g x t
Substituting for t:
v = g x sqrt(2d) / sqrt(g)
v = g x sqrt(2d) / sqrt(g)
v = (g / sqrt(g)) x sqrt(2) x sqrt(d)
v = sqrt(2g) x sqrt(d)

g = 9.8 m/secē
d = 3.8 meters

Thus:
v = sqrt(19.6 x 3.8) m/sec
v = sqrt( 74.5 ) m/sec
v = 8.6 m/sec

1 meter = 39.37 inches, so
v = 8.6 m/sec x (39.37/12) ft/m = 28 ft/sec.
which is 19 mph.

In other words, if you drop something from a height of 12 feet, it will be moving at about 19 miles per hour by the time it reaches the ground. It doesn't matter whether it is a single brick or a 30 story building. After falling 12 feet it will be moving at about 19 mph.

That's about the speed of a collegiate sprinter. (The world record for running the mile is 3:43.13, which is an average speed of 16.134 mph.) If you could sprint that fast and ran into a brick wall the impact might well kill you.

So if the lower 79 floors are strong enough to support a stationary 31 story building, do you think they will be strong enough to support a 31 story building falling at 19 mph?

The answer is emphatically no! But if you are not convinced, then ask yourself this roughly equivalent question. Suppose that you can hold up a 50 lb weight with little difficulty. Do you suppose that you could survive a 50 lb weight falling on you from a height of 12 feet - i.e., at 19 mph? (Warning: Do not try this!)

To answer that question without killing someone, I devised the following experiment. First, I found an easily dividable weight: I used my penny jar. Then I made a support for it: I used a piece of notebook paper stretched over a loaf pan, and taped in place. As you can see, the paper was strong enough to support the jar:

(click on the photo for a close-up)

(I was going to determine the limit to the amount of weight it would support, by adding pennies to the jar until the paper tore, but that's all the pennies I had in my penny jar.)

Then I removed the jar from the paper, and set it aside. I took five pennies from the jar, and taped them together. I stood on a stepstool, reached as high into the air as I could (about 9 or 10 feet from the floor), and dropped the 5 pennies onto the paper from that height. As you can see, even though I didn't drop it from a full 12 feet, the paper still could not withstand the falling pennies:

(I took the pennies out of the loaf pan for this photo; that's them next to the lower-right corner of the pan.) Then I weighed both the five taped-together pennies (12 grams), and the penny jar full of pennies (1372 grams):

As you can see, 5 taped-together pennies weigh just 1/114th as much as the penny jar, yet they tore the paper on the first try. (I didn't try an even smaller stack of pennies.)

You can imagine what would happen if I'd dropped the full penny jar on the paper from 10 feet up. If a 12 gram penny stack broke right though the paper, obviously the paper would hardly have slowed the 1372 gram jar full of pennies at all... just as the lower floors of the WTC towers hardly slowed the fall of the upper floors.

That is experimental proof that a stiff (inelastic) structure which can support a given static load may break when less than 1% of that mass is dropped on it from a height of 10 feet. From that fact, it follows that if the full mass which the structure is capable of supporting is dropped on it from a height of 12 feet, the strength of the structure can be expected to slow the fall by less than 1%.

In the case of the WTC towers, there was a second factor which also slowed the collapse, but not by much. When the top 30 floors of a 110 story building fall 12 feet onto the 79th floor, due to the collapse of the 80th floor, the mass of the 79th floor is suddenly added to the mass of the falling structure. The momentum of a 30 story building falling at 19 mph suddenly becomes the momentum of a 31 story building falling at a slightly smaller velocity. The question is, how much smaller?

p = momentum = m x v
m1 = mass of the top 30 stories
m2 = mass of the top 31 stories = aprox. (31/30) x m1
v1 = velocity before the additional mass is added = 19 mph
v2 = velocity after the mass is added
Momentum is conserved, so:
p = m1 x v1 = m2 x v2 = (31/30) x m1 x v
Solving for v2:
v2 = v1 x (30/31) = 0.968 x 19 mph = 18.4 mph

So you can see that the two factors which slowed the fall of the WTC towers were both very small. The strength of the structure below the point of collapse could be expected to slow the rate of collapse by less than 1%, and the accumulation of additional mass by the falling part of the structure due to the "pancaking" of the lower floors could be expected to slow the rate of collapse by about 3%.

Of course, the above analysis is just about what happened when the top 31 stories fell onto the 79th floor. To predict the progression of the entire collapse, you have to repeat the calculations for each floor. For the next floor, calculate a 32-story building starting with an initial velocity of about 18.4 mph, and accelerating for another 12.4 feet to about 27 mph, and then slamming into the 78th floor. Since kinetic energy is proportional to velocity squared, the falling mass hits the 78th floor with about twice the kinetic energy that the top 31 stories had when they hit the 79th floor. Obviously, the 78th floor could be expected to slow the collapse by even less than the 79th floor did, which is why the building collapsed at nearly free-fall speed.

Dave Burton, Cary, NC USA, Feb. 21, 2007
References:
wtc.nist.gov: National Institute of Standards and Technology reports & information
FEMA: World Trade Center Building Performance Study (or here)
www.9-11commission.gov: 9-11 Commission Report
Scientific American: Preliminary Opinions of M.I.T. Stuctural Engineers (Oct. 2001)
Article: Engineers blame collapses on fires
Article: Faulty Fireproofing Is Reviewed as Factor in Trade Center Collapse
BBC: Q&A: What really happened
WGBH/Nova: Building on Ground Zero
Popular Mechanics: Debunking The 9/11 Myths (March 2005), and Editor's Notes
Book: Debunking 9/11 Myths: Why Conspiracy Theories Can't Stand Up to the Facts, by The Editors of Popular Mechanics
WGBH/Nova: Demolition Woman, Interview with Stacey Loizeaux (1996)
Journal of Debunking 911 Conspiracy Theories
9-11 Myths... Reading between the lies
429truth.com - a campaign to expose the truth of 4-29
Did the U.S. government plan and execute the 9/11 attacks?
xkcd.com

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Response to Static v. Dynamic Loading: Why the WTC Towers Fell So Fast


Green Island Truth hammers a bit on an OCT voodooist

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Ed - this guy's 'arguments' are so full of holes as to be laughable - as is of course the entire OCT (Official Conspiracy Theory). I expect you know that, but have to be polite to the people on your list. Normally I ignore stuff like this, but their condescending attitude really annoys me sometimes ('..simply enough for even a conspiracy theorist to comprehend (I hope)...'

Well. Let me try to explain, for you to forward on, why his little explanation doesn't cut it even closely, and see if I can do it clearly enough so that even an Official Conspiracy Theorist cannot duck around it.

His main argument appears to be that the weight of the top part of the building falling onto the lower part triggered the collapse, as the lower part just could not support all that weight and crumbled like a big house of cards.

I would first direct your readers here - 911 Thought Experiment - it's a piece of my own which they can read or not, but just do the first 'click to the meat' thing and look at the picture for a few seconds, thinking about what they are seeing - it's quite relevant, necessary even, to any 911 discussion involving why or how those huge buildings fell, and fell as they did.

He apparently wants his readers to accept the notion that a large section (12 feet he says) of all the steel beams all around the edge of the building, and all of those 47 or so huge inner columns, on whatever floor first collapsed, just sort of disappeared in an instant, basically evaporated, and thus all that above weight just dropped 12 feet straight down and unimpeded onto the lower section - and then down and down and down and down, each next 12 feet of inner core and outer wall just disintegrating into dust and neatly cut steel beams (just the right size to be loaded onto trucks and hauled off quickly during the removal of evidence, oh sorry cleanup haha) in the same way and dropping onto the next one, and etc and etc.

This might work with a tall house of cards, instant poof!, but with the kind of structural steel and steel-reinforced concrete used in modern highrise construction, as can be seen in that picture, the idea is just laughable.

1. There has never been any attempt made to provide even 'modelled' details to explain that first collapse, which would, if the theory were to be true, mean that somehow that the initial impact and jet-fuel explosion resulted in some very, very serious and concentrated fires all around and throughout the central core, to melt or greatly weaken ALL of that steel at pretty much the same rate, and also ALL of those huge outer structural columns, all around the perimeter, so that after only a few minutes they all just 'collapsed' at the same time (go googling and try to find some pictures of 'collapsing' structural steel that would support this scenario - there aren't any, outside of FX studios...) (and yes, there have been 'models', but very notably not dealing with this all-important initiation at all - for very understandable reasons, as I describe here "ooee big fire, plane crash - all fall down go boom!!!' - is not actually useful modelling). When you read that in black and white, it starts to become clear why no attempt has ever been made to do this - there is no possible believable scenario that leads to the OCT conclusion of 'just crumbled like a giant house of cards golly!!!'. So the boogie-voodoo has to come out. The only vaguely plausible scenario would have been that the impact and resulting fires weakened one side of the structure enough so that the center of gravity of the upper section became skewed and the remaining structure not strong enough to carry it, so the top part of the structure just slowly overcame the great strength of that steel matrix, and fell over, and then resulting in god only knows what damage to the lower structure, still fundamentally sound, as, all OCT stuff aside, there was not enough aviation fuel to leak down elevator shafts and cause any sort of significant fires at all, after most of it was consumed in the initial fireballs. It's hard to imagine what might have happened in that scenario, as that huge mountain of steel below the falling section would have put up a huge amount of resistance to falling in any way - but what is obvious to anyone whose brain hasn't been burned out by too much tv watching is that there is simply no way that the initial impact and those small fires would have resulted in what we saw - the apparent disintegration of all of the steel at the level of one floor, resulting in the crumbling of that huge building. Or those huge buildings.

2. Let us also not forget to note the somewhat important point that although the interior floors of those buildings were each 12 feet or so high, the building itself was not constructed in 12-ft tall sections stacked one on top of another like a kid playing with his little construction kit might do - this would be very poor construction technique for serious buildings, and no doubt there'd be buildings falling down all over the place if it was ever used for anything over 5 or 6 stories tall. But with the WTC (and any other major highrise constructed in a similar way), the inner columns were essentially a 1,000+ foot tall matrix of solid steel columns, welded and bolted all along their length to provide essentially a single unit, very much NOT stacked 12-ft sections ready to behave as the OCT attempts to theorize, and the outer wall segments - which, let us not forget, were load-bearing steel, not aluminum siding with no strength to speak of, were staggered across more than one floor, all the way up and around, so this notion of everything collapsing in 12-ft floor-size blocks is just a non-starter to anyone who has any idea of the basics of highrise construction. To someone who gets their information from personal research rather than Popular Mechanics, at any rate. There simply were no 12-ft segments stacked one on top of the other to collapse like a stack of records. The individual floors were fastened (strongly!) between the central column and outer wall, and it is conceivable that a SEGMENT of a floor would become weakened and collapse - but the rest of the floor around the same level, less weakened or not weakened at all, would resist that collapse, and the notion that an entire floor would 'globally' just give out all at once and fall at a single moment to the floor below, and thus stress that floor to the point of again complete collapse so both floors fell to the next, and so on and on - and somehow these collapsing floors took along the massively strong inner column matrix and outer walls with them - well, you can do it in comic books or FX studios where all is possible, but this sort of thing doesn't happen in real life (it's a bit interesting that the last reference in this piece, along with such stalwarts as Popular Mechanics, is a place called xkcd.com - which, if you check it out, is - a comic book!!).

3. His 'try it yourself!' 'proof' of dropping a 50-lb weight onto yourself from 12 feet is equally shallow and stupid, really (only a person 'educated' in America (sadly that includes Canada the last couple of decades - too much tv really does have a serious deleterious effect on the brain) could absorb this sort of nonsense without some 'wtf??' warning lights flashing immediately and very brightly. The main point, of course, is simply that it wasn't Atlas or some other flesh and blood figure holding up that upper section - it was an absolutely huge amount of similar construction steel and steel-reinforced concrete. For his example, instead of dropping a 50-lb chunk of steel on your poor flesh-and-blood-and-bone head, what would happen if you dropped a 50-lb chunk of steel on a 500-lb chunk of steel? Is he going to sit there and put forth the notion that that 500-lb chunk of steel would instantly collapse? I doubt he'd actually want to try that one on anyone with intelligence above the level of 'cow' or something - even rubes at the fair can only be pushed so far. Although it seems there are a lot of such people in American schools these days. But hopefully not on your list, Ed.

Get the guy to explain how dropping a roll of copper pennies on a single sheet of paper stretched across a bread pan has anything at all to do with dropping a chunk of steel and concrete on a larger chunk of steel and concrete? There is no equivalency whatsoever - and it is pretty foolish (and insulting to your audience, really, or else to yourself) to pretend there is. (listen to me being polite!)

4. His many lines of 'complicated physics' calculations are basically completely out of any relevant context, and useless and meaningless - 'sound and fury signifying nothing', as another guy once put it, the basic con trick of impressive looking or sounding smoke and mirrors to distract the credulous listener from more important things. What is needed, and would be interesting, is a calculation showing the residual strength of the lower 80 stories of the WTC, the inherent strength in that massive amount of welded and bolted interconnected steel and steel-reinforced concrete, and all of those floors fastened with more welds and bolts to the inner core and outer walls, and an indication of how dropping a weight equivalent to the upper 30 stories would compromise that total inherent strength to the point of not only collapse, but essentially instantaneous, universal crumbling like dropping that 50-lb chunk of steel not on a bigger piece of steel but on a small piece of sandstone or something - this is NOT a sheet of paper and a roll of pennies or a chunk of steel and your head. And the reason they don't do this, I would suggest, is because the answer to anyone who has any understanding at all of materials science and physics and the immense strength of modern construction steel and reinforced concrete buildings is basically a belly laugh and a 'no way Jose!!!!'. Telling us how fast the upper section would drop if it actually had 12 resistance-free feet to drop (which it assuredly did NOT), and getting big googoo eyes and saying 'just imagine!!!!' - is nothing more than a congame, trying to fool the rubes at the circus who know nothing about this kind of thing and are susceptible to this kind of trick from fast-talkers in fancy suits. Dropping a 50-lb chunk of steel on your head is NOT the same as dropping that steel-concrete section onto an even bigger steel-concrete base. As any non-rube can clearly understand.

and finally 5. Let us have a quick look at the idea of 'friable' as well, as it is related to the last and very applicable here, and we might as well go all the way to the coup de grace since the guy is already in his death throws, but let's keep him down for good, bad ideas have a way of returning over and over again. I am sure you know what this word means - if you get a piece of sandstone, say, or a solid glass ball or something like that, and give it a good whack with a big hammer, it just sort of universally explodes into small pieces - that's 'friable', no internal interconnection strength - and that is what this guy, and the others like him, want us to believe happened to the WTC buildings - big whack with the upper section of floors falling unimpeded to the lower larger section, and boom!! it just exploded from the force like a piece of sandstone!! - you can see it all the time in Marvel comics books and hollywood movies, right?!?!?! But the most cursory ability to think (helped along by a look at the picture I refer to earlier) will quickly lead one to the fact that actually modern highrise buildings are not constructed of sandstone or sandstone-like stuff, or sheets of paper and elastic bands, they are constructed of serious matrices of seriously welded and bolted interconnected steel and steel-reinforced concrete - and these materials are basically the reverse of friable, they have huge resistance to falling apart, they are a huge, interconnected matrix with tens of thousands of strong bonds, all or most of which would need to be broken (at huge energy input) for the thing to fall as it did - they have a huge resistance to 'exploding into small pieces' when struck by anything at all. Try it sometime. Get the smallest piece of steel you can find, and the biggest sledgehammer, and hit it. Again and again and again. You can bend it, maybe, if you're big and strong enough, and deform it, but you cannot 'explode' it. Even light steel - look at cars that have been in major accidents and burned as well - all bent and twisted from force, but no disintegration anywhere. That is just not what steel behaves like. Steel is the very antithesis of 'friable' - it takes huge force to damage steel - and just think of that earlier picture and that mountain of steel. And to suggest an entire building (3 actually) just 'exploded' like a piece of sandstone is something for the rubes. Not me. Not you, I expect. (although one would be remiss in not noting that this kind of 'explosion' is actually seen rather commonly - in controlled demolitions, where the people planting the explosives do so carefully, with just that purpose in mind, to ensure that those bonds are broken in sufficient, carefully calculated places to weaken that overall integrity to the point where the building will collapse, and break up at regular intervals, and fall straight down, using the force of gravity to assist in the destruction, and making sure it falls into its own footprint to minimise damage to the surrounding structures... oddly enough, more or less exactly as we saw on a certain 91101....)

Oh well, that should be enough for now. Good luck, E....

References:
One intelligent, independent brain, widely read and including experienced BS-detector. (there's lots in the modern mainstream media and political circles to practice on)



- and final comment, a reply from the physics 'expert':

Dear --,
You are obviously too smart to be duped by the nonsense that We feed to the sheep. Perhaps you would like to join us? We need bright young men like you in The Conspiracy. All the structural engineers in the world have already signed up, so why not you, too?

- guess that says it all. The schoolkid caught in his attempted con, unwilling to admit anything or lose face, offers the smart remark, and heads for the hills. Certainly impresses me. But once again, the condescending OCTers, when challenged to a real debate with real facts, fold like a cheap cigar.
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