this is not true. we have footage that shows the collapse of the inside of the building for the first few seconds, and arial footage showing it from the inside.
On 2/27/07, Stephen A. Lawrence <[EMAIL PROTECTED]> wrote:
Nick Palmer wrote: > I do not think they went down in freefall, after a few seconds the rate > looks like it nearly stabilises as the resistance from the undamaged > structure below just about cancels the acceleration of the mass above - > I suspect this figure of 9 or 10 seconds need to be examined from the > videos and the "free fall time" needs to recalculated... If it "pancaked" down, no matter what the cause, it should have fallen at nearly free-fall speed. By "nearly" I mean within a second or so, top to bottom. This is simple physics; I worked out part of it in an earlier email to this list -- enough to see what the result looks like. Anyone with time on their hands and an understanding of x = (1/2)at^2 should be able to carry it through to the bottom. The result may not jibe with intuition, so I found it a worthwhile exercise to at least start. The "hesitation" at each floor before it gave way should have been miniscule, simply because as the mass falls, the next floor it hits will either break away at (or before) the moment of maximum stress, /or/, if it survives the moment of maximum stress, it won't break and the collapse will stop at that floor, because after the initial shock the stress on the supports declines. If the maximum stress doesn't break it, smaller stresses won't either. The moment of maximum stress comes when the shock wave from the impacting mass reaches the supports, which is essentially instantaneous: the shock wave travels through the material of the floor at the speed of sound, and it doesn't have very far to go. So, again, whether the demolition was controlled or uncontrolled, caused by an airplane, thermite, a nuclear bomb, or the Tooth Fairy, the fall speed should have been very much like what we see in the videos. Something else worth pointing out: WE CAN'T SEE THE COLLAPSE in the video. We can see the cloud coming out of the building, which shows where all the windows have blown out. But, the floors were falling /inside/ the building, and we can't see them fall -- we can only see the results of the fall. It is quite conceivable that the falling mass inside the building actually "leads" the cloud and flying debris we see on the outside of the building by several floors. > > Nick Palmer
-- That which yields isn't always weak.
