Originally posted by: kylebisme
What brought down WTC7 was a near instantaneous removal of approximately 8 stories of structural support. This is proven by the following two facts; (1) acceleration indistinguishable from free fall is only possible in absence of any notable resistive force, (2) WTC7 dropped with period of acceleration indistinguishable from free fall for approximately 105 feet. To substantiate these facts:
1) This is simply inhernet to the deffition of the term free fall, as
documented here:
free fall
?noun
1. the hypothetical fall of a body such that the only force acting upon it is that of gravity.
Note they say "hypothetical" as there is always at lease some air in the way preventing a falling object to accelerate at the full acceleration of gravity, and the absence of even the any resistive force of air is only possible in the hypothetical case of a complete vacuum, but acceleration indistinguishable from free fall means that what little mass is in the way is not enough to provide any observable resistive force. For those who don't understand why this is, but would like to, I recommend starting
here, and feel free to ask questions on this matter as needed.
2) While WTC7's period of free fall acceleration was prevoisly denyed by the government agaencies which investgated the event, due to the widely avalable video evidence NIST was eventually persuaded to to admit this fact,
as documented here:
In Stage 1, the descent was slow and the acceleration was less than that of gravity. This stage corresponds to the initial buckling of the exterior columns in the lower stories of the north face. By 1.75 s, the north face had descended approximately 2.2 m (7 ft).
In Stage 2, the north face descended at gravitational acceleration, as the buckled columns provided negligible support to the upper portion of the north face. This free fall drop continued for approximately 8 stories or 32.0 m (105 ft), the distance traveled between times t = 1.75 s and t = 4.0 s.
...
From these facts, NIST suggests distinct stages where an initial buckling of columns on one face of the building allowed the point on the they measured roofline to drop approximately 7 feet, which then allowed for 105 feet of free fall to happen next. Note that while NIST only refers to the one point on the roofline, any video of the event will show that after the initial sagging of the roofline towards the middle, the entire roof falls symmetrically though the period of free fall and beyond, until notably asymmetrical resistive force well further down causes it to tilt. You can observe the fall of WTC7 from best two angles I've seen, compared to what little NIST released of their simulations, in
this video.
Any other video of the event in existence will show the same period of free fall, and please don't hesitate to dig up more to see for yourself, and post whatever videos of the event you like. Regardless, such video evidence demonstrates that for the period of free fall, not only were the north face columns not providing any notable support, neither were those of any other face, or all of the mass that made up the floors and everything else in the building.
How exactly that complete removal of structural resistance was accomplished would require a proper investigation, as the ones we've had so far have only obscured the fact that impact damage and office fires simply can't explain anything of the sort. To view clearly visible examples of a near instantaneous removal of multiple stories of structural support for comparison sake, see the hydraulically initiated demolitions in
this video. As for examples of where free fall acceleration can be observed without removal some distance of structural support by an outside force; you simply won't find even a one, as it is physically impossible.
So, we are all left with a choice here; have faith in the offical story of the fall of WTC7, or accept the fact that the offical story stands in contradction to demonstatable physical reality. Which do you choose?
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