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It was more like halve of free fall speed. The study I linked shows it is possible. Why is that scientific study wrong, and your opinion correct, of which you still did not say what you based it on?
You obviously also do not understand it well enough to refute it. So unless another study or scientist refutes it by showing why it is wrong, I will stand by it, and not by your gut feeling. Show me the study that proves it is wrong, and we have something to discuss. Until then, I have no reason to believe its wrong. Intuitively it makes sense to me. What we currently have is several studies that show that the progressive collapse is inevitable, and none it is inconceivable. Why should I go by your gut feeling, and not by the science?
Originally posted by Nathan-DThe collapse times themselves are largely irrelevant: free-fall is better judged by analyzing acceleration of the collapse at every point in time, as opposed to just two points of "start" and "end" which themselves cannot be accurately designated, due to the smoke and unpredictability of the seismic data. I would suggest picking more reliable points of data than the two-point measurement that is total collapse time, such as acceleration of the still visible parts of the structure, possibly compared to actual free-falling debris nearby. The first method is largely meaningless and inaccurate - especially due to the obscuring canopy of smoke - but can also be altered beyond meaning to either improve or negate free-fall descent.
I think the collapses can most realistically be estimated at 11-14 seconds, but that actual velocity study is much more relevant. Ironically, even the most egregious claims of 20 seconds or more do not exceed average estimations for known explosive demolitions (i.e. 200% free-fall). The official investigations have gone on record as estimating the collapse times at 10-12 seconds. For a non-hypocritical proponent of the official investigations that would be the end of that. I think I'll also take this opportunity to quote NIST: "since the stories below the level of collapse initiation provided little resistance to the tremendous energy released by the falling building mass, the building section above came down essentially in freefall, as seen in videos".
I understand the conservation of angular momentum and equilibrium forces. If the top-section was seen pivoting away from its centre of gravity then one would expect this to continue, not straighten up and proceed to collapse symmetrically straight-down through the tower. This makes sense to me intuitively. I would link you to papers by Gordon Ross but I seriously can't be bothered.
Originally posted by JIMC5499
Thank God a few people know what they are talking about.
For those of you who don't, try this experiment.
Take a 24 oz styrofoam cup and a brick. Lay the cup on it's side and then gently place the brick on top of it. The brick will crush the cup. Now, take another cup and place it upside down and then gently place the brick on top of it. The cup will support the weight of the brick. The walls of the cup transmit the load from the brick to the ground. Now pick up the brick and hold it 1 inch above the cup and then drop the brick. You will crush the cup. If you have another cup, put it upside down and place the brick on top of it. Now shoot the cup with a BB gun. The hole in the cup will weaken the sides of the cup enough that the brick will collapse it.
The towers were designed like two square shaped cups, one inside the other. The outside structure of the towers and the inner core were designed to transmit the loads to the ground. The floors were suspended between the outer structure and the inner core. Each floor was only meant to support it's own load and to transmit that load to the outer structure and the inner core. The purpose of this was to allow each floor to have large open areas without the building's structure getting in the way. Frankly I'm suprised that the towers stayed up as long as they did.
Lets assume that your are correct, and the pivoting should have continued. Why would that not be true if demolition charges or thermite was used? Shouldn't the pivoting just as well continue in that case? If not, why?
Ok well, I kinda miss your point here. Studies show that the observed fall speed is consistent with calculations.
Originally posted by Nathan-D
It did, until it was engulfed in cloud of smoke.
What calculations may these be?
So your claim is that it did pivot further? Even though that seems not to be supported by video evidence, how exactly does that disproof a progressive collapse?
So even if the top section would disappear completely at that point, the collapse would still continue, driven by the mass of the floors already collapsed.
The ones that are used in the models in the paper and its references I linked.
Originally posted by Nathan-D
It is supported by video evidence. You clearly see in the videos it pivot outwards as it becomes displaced from its centre of gravity (and then it suddenly gets engulfed in a cloud of dust). The image below shows how far the top-section pivoted. If the top-section was experiencing any resistance from the tower below it would have continued to pivot around its centre of mass, so the side which is above the building is being pushed up, whereas the side overhanging the building is pushing down. This should create a rotational force (torque) pushing the top-section outwards.
What do you base this assumption on?
Care to post them?
Originally posted by Wide-Eyes
Julian Assange says 9/11 wasn't a conspiracy by the American government.
Maybe it was allowed to happen...
Originally posted by JIMC5499
Thank God a few people know what they are talking about.
For those of you who don't, try this experiment.
Take a 24 oz styrofoam cup and a brick. Lay the cup on it's side and then gently place the brick on top of it. The brick will crush the cup. Now, take another cup and place it upside down and then gently place the brick on top of it. The cup will support the weight of the brick. The walls of the cup transmit the load from the brick to the ground. Now pick up the brick and hold it 1 inch above the cup and then drop the brick. You will crush the cup. If you have another cup, put it upside down and place the brick on top of it. Now shoot the cup with a BB gun. The hole in the cup will weaken the sides of the cup enough that the brick will collapse it.
The towers were designed like two square shaped cups, one inside the other. The outside structure of the towers and the inner core were designed to transmit the loads to the ground. The floors were suspended between the outer structure and the inner core. Each floor was only meant to support it's own load and to transmit that load to the outer structure and the inner core. The purpose of this was to allow each floor to have large open areas without the building's structure getting in the way. Frankly I'm suprised that the towers stayed up as long as they did.
edit on 30-11-2010 by JIMC5499 because: added more info
Originally posted by SphinxMontreal
"The government covered it up pretty good since a lot of people believe it wasn't an inside job."
Actually, they did a piss poor job of covering it up. It doesn't matter though, because most Americans aren't too bright when it comes to these sort of things. They're more interested in lousy TV shows and beer that tastes like urine.