Again, you havent given any reason for us to talk about it. It doesnt matter if the section rotated or not... the fact remains it hit the rest of the building and brought it down. Make a sensible argument and people might discuss it. Keep spouting nonsense and nobody will take you seriously
9/11 was an inside job
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Again, you havent given any reason for us to talk about it. It doesnt matter if the section rotated or not... the fact remains it hit the rest of the building and brought it down. Make a sensible argument and people might discuss it. Keep spouting nonsense and nobody will take you seriously
Not acceptable to YOU.
But to me YOU haven't demonstrated that you can handle simple trigonometry.
You made no comment on the 67 ft versus 43 feet. So I don't know if you regard the numbers as correct or not or don't even know what they have to do with center of mass.
psik
I have made no comment on them because they do not matter, and in regards to the 67 ft vs 43 ft, I don't even know what you are blubbering about.
Let me spell this out for you so even a first grader could grasp it:
None. Of. That. Matters. Period.
The top of the building... it weighs a lot. The building is designed so that each floor supported itself, not the weight of the floors above it. Thus, when a lot of weight from a lot of floors above fell on the floor below, it fell onto the floor below it, which then fell to the floor below it, etc etc etc.
The angle that the top portion impacted the lower portion at doesn't matter worth a damn.
The reason you are hung up on this angle thing is simple; you have no facts to back any kind of argument up with, so instead you are trying to deflect attention away from the actual argument and onto ideas that have not been studied for the simple fact that they are not relevant to anything. Of course nobody studied the angle of the buildings top portion before it fell - it doesn't need to be studied. The reason it tilted is simple - the portion underneath was giving way. The angle it fell at doesn't matter - the simple, plain fact remains that it impacted the portion under it and caused a total collapse.
Stop your pointless tangents and provide some shred of evidence to support the idea of this thread... or, if you cannot do so, let the thread die already.
Alright, I decided just for the heck of it to actually sit down and do some quick calculations, and here's what I come up with:
Consider a skyscraper with uniform mass distribution on each floor, and for simplicity divide it into an infinite number of infinitely small floors, treating the whole building like a uniform mass of concrete. Assume that each of these infinitesimally thin floors gives no resistance as it's hit by the mass falling from above, other than having its inertia overcome as it instantly accelerates to match the speed of the falling debris. It's a calculus problem, but not a terribly difficult one.
If $$h$$ is the distance the roof falls after time $$t$$ has elapsed starting from rest, and $$g$$ is the free fall rate of gravitational acceleration towards the ground, then we have the following differential equation to describe the roof's fall:
$$h\left(\frac{d^2h}{dt^2}-g\right)+\left(\frac{dh}{dt}\right)^2=0$$
As it turns out when you work out the derivation to this equation, the mass density of the building doesn't affect the fall time in this simplified model, as long as we assume that it's uniform. There are two solutions to this equation: the first solution is $$h=0$$ for all times, corresponding to the building not collapsing at all. The second solution is $$h=\frac{1}{6}gt^2$$, correponding to an accelerating fall buffered by each floor's inertia as it's hit.
With the falling solution, we can invert and solve for time to get $$t=\sqrt{\frac{6h}{g}}$$, which is a factor of $$\sqrt{3}$$ times longer than we would expect the roof to fall the same distance in freefall. It looks to me like Psikeyhacker's assertion of "triple free-fall time" being the minimum realistic fall time is more likely the result of bad high-school level calculations, since he's overestimating the fall time by a factor of roughly $$\sqrt{3}$$ (breaking the skyscraper into a finite number of floors as he does likely doesn't make much difference, although I'm willing to consider checking it directly if Psikey shows his calculations first).
According to this equation, the South Tower should have collapsed in roughly 16 seconds, and I think the actual figure is quoted by some sources as 17 seconds.
Consider a skyscraper with uniform mass distribution on each floor, and for simplicity divide it into an infinite number of infinitely small floors, treating the whole building like a uniform mass of concrete. Assume that each of these infinitesimally thin floors gives no resistance as it's hit by the mass falling from above, other than having its inertia overcome as it instantly accelerates to match the speed of the falling debris. It's a calculus problem, but not a terribly difficult one.
If $$h$$ is the distance the roof falls after time $$t$$ has elapsed starting from rest, and $$g$$ is the free fall rate of gravitational acceleration towards the ground, then we have the following differential equation to describe the roof's fall:
$$h\left(\frac{d^2h}{dt^2}-g\right)+\left(\frac{dh}{dt}\right)^2=0$$
As it turns out when you work out the derivation to this equation, the mass density of the building doesn't affect the fall time in this simplified model, as long as we assume that it's uniform. There are two solutions to this equation: the first solution is $$h=0$$ for all times, corresponding to the building not collapsing at all. The second solution is $$h=\frac{1}{6}gt^2$$, correponding to an accelerating fall buffered by each floor's inertia as it's hit.
With the falling solution, we can invert and solve for time to get $$t=\sqrt{\frac{6h}{g}}$$, which is a factor of $$\sqrt{3}$$ times longer than we would expect the roof to fall the same distance in freefall. It looks to me like Psikeyhacker's assertion of "triple free-fall time" being the minimum realistic fall time is more likely the result of bad high-school level calculations, since he's overestimating the fall time by a factor of roughly $$\sqrt{3}$$ (breaking the skyscraper into a finite number of floors as he does likely doesn't make much difference, although I'm willing to consider checking it directly if Psikey shows his calculations first).
According to this equation, the South Tower should have collapsed in roughly 16 seconds, and I think the actual figure is quoted by some sources as 17 seconds.
Yeah, that is what I figured. You lost it with the word 'sine'.
psik
I would rather enjoy seeing you point out where I have mentioned the word "sine" anywhere... if you are trying to claim I do not understand the word "sine", then you are gravely mistaken.
HOWEVER
Given that you have, once again, failed to produce any evidence, I take that as your conceding the argument and, on those grounds, I accept your withdraw from the debate.
That - is impressive.
And the whole point behind my calculation is to show that Psikeyhacker isn't much of one either, and yet if it were up to him, someone would have probably already been hanged for this "insider conspiracy".
Sorry dude, you just blew it right there. It is probably impossible to make such a skyscraper over 1000 feet tall hold itself up. It is because the bottom must support so much more weight that steel must be used in the first place.
Making assumptions that we KNOW must be faulty in order to make the math simpler and then try to claim the math has something to do with reality is illogical nonsense.
I showed how changing the mass distribution altered the Potential Energy SIX YEARS AGO.
http://breakfornews.com/forum/viewtopic.php?p=31763#31763
How could the lighter weaker portion of the top of the north tower destroy and accelerate the stronger heavier lower portion of the north tower to bring the whole thing down in less than 26 seconds? That is the problem that has not been addressed in 12 years. And then people do not even demand accurate data on the building.
So maybe you can impress people who can't do trigonometry with calculus that does not apply because it is based on assumptions that are TOO SIMPLE.
BIG DEAL!
psik
Quite easily. Give me your estimates for the mass of the upper part of the building and I will show you how. Or if you don't know I will make some basic assumptions and show you how.
Or if you are completely clueless just keep posting crap.
Sorry dude, you just blew it right there. It is probably impossible to make such a skyscraper over 1000 feet tall hold itself up. It is because the bottom must support so much more weight that steel must be used in the first place.
Making assumptions that we KNOW must be faulty in order to make the math simpler and then try to claim the math has something to do with reality is illogical nonsense.
I showed how changing the mass distribution altered the Potential Energy SIX YEARS AGO.
http://breakfornews.com/forum/viewtopic.php?p=31763#31763
How could the lighter weaker portion of the top of the north tower destroy and accelerate the stronger heavier lower portion of the north tower to bring the whole thing down in less than 26 seconds? That is the problem that has not been addressed in 12 years. And then people do not even demand accurate data on the building.
So maybe you can impress people who can't do trigonometry with calculus that does not apply because it is based on assumptions that are TOO SIMPLE.
BIG DEAL!
psik
Oh my god... you really are ignorant in this, aren't you...
"it is probably impossible to make such a skyscraper hold itself up"... WHAT? What are you smoking? Do you even know the first thing about structural engineering? Like, at all? Are you capable of understanding how weight distribution works in the slightest?
Just... UGH! Your ignorance is infuriating enough, but the fact that you tout it about like a flag of honor while shouting down every shred of evidence brought to you that shows just how little you understand is absolutely asinine! You, sir, are a disgrace to science!
To top it off, you claim that CptBork's calculations are wrong, yet you provide NO scientific evidence for it! AUGH! If it were up to people like you, we would be thrust into another Dark Ages!
How hard is it to understand? The building didn't fail AT THE FOUNDATION! It failed, layer by layer, as each floor was subjected to far more weight from the debris above than it's supporting structure was designed to hold! Yet you keep saying that such a thing is impossible... LOOK AT THE GODDAMN VIDEOS OF IT! It happens RIGHT before your very eyes! Unless, of course, you wish to submit that the US Government is so involved in this master conspiracy that they actually used hologram projectors to make it LOOK like the building failed that way... and honestly, such a crazy claim wouldn't' surprise me at all coming from you! If it were up to me, such a bastardization of science would be worth being removed from here on its own merit... unfortunately as this is the crank/pseudoscience section, such ramblings of madmen are kind of expected, and are to be tolerated...
I have tried to remain civil, but you absolute lack of regard for science, the scientific methodology, and anything resembling fact or logic is absolutely infuriating beyond words, especially since it is so obvious there is some level of intelligence in that brain of yours!
psikeyhackr
So you really DON'T know the first thing about those buildings. No wonder you're so confused.
This is a photo of the construction. The "porch" is going to be part of the ground level. Everything below that is a steel framed concrete structure, everything above that is a perimeter frame/core structure with truss floors designed only for that floor's weight, they do not support floors above or below themselves and they transfer their weight to the outer steel frame(a square tube of steel)and the elevator core(the steel column structure in the middle). There is no structural concrete in either tower above the level of the "porch". The floors were simple trusses, covered by corrugated steel pans and 4 inches of lightweight concrete.
Notice the large areas of the truss floors outside of the core and surrounded by the perimeter frame. They were all basically identical(except the three equipment floors)and did not share any of the vertical loads of the building, that was entirely supported by the perimeter and the core. Only the steel thickness of that perimeter frame and the size of the vertical columns in the core got bigger and stronger nearer the ground. The floors were no stronger on the 15th floor than they were on the 90th, they were all equally weak(IE just strong enough for each floor's loads).
They were attached at each end by angle iron brackets designed to carry only that floors vertical load to the frame and core. All vertical loads in that building were ONLY carried by the perimeter frame and the core(approximately 50/50, though only the frame carried wind loads)all the floors had no structural function other than holding up office chairs and desks, plus bracing the perimeter frame and core in the vertical position through dampers. Most of those angle irons were stripped off of the frame and core steel found in the rubble, the floors provided virtually zero resistance to the falling debris, it might as well have been empty space as far as slowing the falling steel pieces. And, unless braced in a perfectly vertical orientation, the perimeter frame and core would have just fell over, breaking into it's component pieces(as we saw it do on 911).
The assumption of roughly equal distribution of mass fits pretty well in the Twin Towers, the frame and core were only about 35% of the total weight of the structure above ground and the differences in steel weight between top and bottom only a factor of ~3.5(IE the bottom steel was about 3.5 times the weight of those on the top of the same length). All floors except the equipment floors were identical in weight from top to bottom, they were built from identical sections of truss, floor pans and four inches of lightweight concrete, they did not get stronger or weaker with their position in the buildings and played no part in supporting anything but the floor load on that one floor, transferring that load to the frame and core.
But let me ask a question. How much resistance is encountered by a marble dropped down a vertical tube? Answer, the same amount a disconnected steel beam experiences as it falls past it's former beam mates. And to that falling steel beam a floor of the Twin Towers was a spider web, for all the good it could do to stop that steel beam(and all it's brothers and sisters, aunts, cousins and nephews)once they fell 12 feet(one floor)according to the real scientists at NIST. It is the details of how those buildings were constructed, their strengths and weaknesses, the damage and fires plus the incredible power of gravity examined in the light of physics and evidence that makes the NIST report the last word on the physics of those events. Call Shrub a co conspiritor if you like, but we know how and why those building fell, some seriously deranged fanatics, poisoned by their "peaceful" religion(or rather a perversion thereof)trying to earn their 72 virgins(and 20 some odd young boys, by the way)flew 250,000 lb aircraft into them at nearly 500 mph. Period. Everything else is just detail.
Grumpy
So you really DON'T know the first thing about those buildings. No wonder you're so confused.
This is a photo of the construction. The "porch" is going to be part of the ground level. Everything below that is a steel framed concrete structure, everything above that is a perimeter frame/core structure with truss floors designed only for that floor's weight, they do not support floors above or below themselves and they transfer their weight to the outer steel frame(a square tube of steel)and the elevator core(the steel column structure in the middle). There is no structural concrete in either tower above the level of the "porch". The floors were simple trusses, covered by corrugated steel pans and 4 inches of lightweight concrete.
Notice the large areas of the truss floors outside of the core and surrounded by the perimeter frame. They were all basically identical(except the three equipment floors)and did not share any of the vertical loads of the building, that was entirely supported by the perimeter and the core. Only the steel thickness of that perimeter frame and the size of the vertical columns in the core got bigger and stronger nearer the ground. The floors were no stronger on the 15th floor than they were on the 90th, they were all equally weak(IE just strong enough for each floor's loads).
They were attached at each end by angle iron brackets designed to carry only that floors vertical load to the frame and core. All vertical loads in that building were ONLY carried by the perimeter frame and the core(approximately 50/50, though only the frame carried wind loads)all the floors had no structural function other than holding up office chairs and desks, plus bracing the perimeter frame and core in the vertical position through dampers. Most of those angle irons were stripped off of the frame and core steel found in the rubble, the floors provided virtually zero resistance to the falling debris, it might as well have been empty space as far as slowing the falling steel pieces. And, unless braced in a perfectly vertical orientation, the perimeter frame and core would have just fell over, breaking into it's component pieces(as we saw it do on 911).
The assumption of roughly equal distribution of mass fits pretty well in the Twin Towers, the frame and core were only about 35% of the total weight of the structure above ground and the differences in steel weight between top and bottom only a factor of ~3.5(IE the bottom steel was about 3.5 times the weight of those on the top of the same length). All floors except the equipment floors were identical in weight from top to bottom, they were built from identical sections of truss, floor pans and four inches of lightweight concrete, they did not get stronger or weaker with their position in the buildings and played no part in supporting anything but the floor load on that one floor, transferring that load to the frame and core.
But let me ask a question. How much resistance is encountered by a marble dropped down a vertical tube? Answer, the same amount a disconnected steel beam experiences as it falls past it's former beam mates. And to that falling steel beam a floor of the Twin Towers was a spider web, for all the good it could do to stop that steel beam(and all it's brothers and sisters, aunts, cousins and nephews)once they fell 12 feet(one floor)according to the real scientists at NIST. It is the details of how those buildings were constructed, their strengths and weaknesses, the damage and fires plus the incredible power of gravity examined in the light of physics and evidence that makes the NIST report the last word on the physics of those events. Call Shrub a co conspiritor if you like, but we know how and why those building fell, some seriously deranged fanatics, poisoned by their "peaceful" religion(or rather a perversion thereof)trying to earn their 72 virgins(and 20 some odd young boys, by the way)flew 250,000 lb aircraft into them at nearly 500 mph. Period. Everything else is just detail.
Grumpy
Good thing the ancient Romans didn't employ you as an engineer, or we'd have no aqueducts and bridges to look at today.
I'm not even sure you know how to properly calculate potential energy in the first place, given a certain comment you wrote about it earlier. Furthermore, you spoke about "momentum conservation" (an incorrect reference to what you should have called "inertia"), and for the purposes of calculating this type of collapse, potential energy isn't relevant anyhow.
So maybe you can impress people who can't do trigonometry with calculus that does not apply because it is based on assumptions that are TOO SIMPLE.
BIG DEAL!
I didn't use any trigonometry in the problem, you only think I did because you suck at math, you're just another idiot with a keyboard rather than a trained structural engineer we can trust with peoples' safety. Besides, it's rude to bellow with food in your mouth. Go have another beer, Homer.
The man who apparently can't do algebra talks about ignorance.
His calculations can be correct without having anything to do with any real skyscraper.
They are not uniform all of the way down so his calculations have nothing to do with any real structure over 1000 feet tall. He admitted his assumption. The same one Frank Greening made.
It is an assumption that makes for easier math.
psik
Actually I am the only one who has built a physical model that does what he says and I have not accused anyone of being crazy.
Physical models are incapable of evaluating sanity but shouldn't people that are correct and sane be able to build models that do what they say?
psik
I would like you to provide some evidence that I cannot do algebra (interesting since I passed it in high school and have taken up to, and passed through, Calculus 3... never again though, ugh)
So you have built a perfect to-scale model of the twin towers and then rammed a to-scale aeroplane into it with burning fuel and all?
I would like to see some video evidence of this please.
No; google the "square-cubed" law.
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