Quote:
Originally Posted by Chanda  Are you a physicist? Physicists say it isn't possible, except by controlled demolition:
Dave Heller, a builder with degrees in physics and architecture: "The floors could not have been pancaking. The buildings fell too quickly. The floors must all have been falling simultaneously to reach the ground in such a short amount of time. But how?" |
This guy only seems to exist on 911 truth websites (just like the "MIT engineer" Jeff King) so i doubt his credentials. But if you look at the collapse of the towers you see that they collapse from the top down. If they were falling simultaneously like he says, then the debris should start rising up from the collapse of the lower floors early on but it doesn't. Also if the floors fell simultaneously then you would see the entire building collapse simultaneously rather than it crumble from the top down.
Quote:
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Physicist Steven Jones: "the Towers fall very rapidly to the ground, with the upper part falling nearly as rapidly as ejected debris which provide free-fall references . . . . Where is the delay that must be expected due to conservation of momentum---one of the foundational Laws of Physics? That is, as upper-falling floors strike lower floors---and intact steel support columns---the fall must be significantly impeded by the impacted mass. . . . [b]ut this is not the case. . . . How do the upper floors fall so quickly, then, and still conserve momentum in the collapsing buildings? The contradiction is ignored by FEMA, NIST and 9/11 Commission reports where conservation of momentum and the fall times were not analyzed"
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From F.R Greening's paper
"Energy Transfer In the WTC collapse" 
The towers collapsed far from free fall speed, giving more than enough time to account for the conservation of momentum. The observed collapse of the towers also is very similar to the theoretical collapse that Greening calculates.
