Hello, Right. We don't have to rely on what it looked like.
The most precise measurements of the collapse were made by Frank Greening, who analyzed the video record to track the motion of a fixed point at the top of each tower until it was obscured by dust. The results are on page 902 of this paper in the Journal of Engineering Mechanics:
http://www.civil.northwestern.edu/pe...Papers/476.pdf
For example, the North Tower fell 30 meters in the first 3 seconds, an average acceleration of
2x30 / 3^2 = 6.67 m/sec^2 = 0.68g - two thirds of free fall.
9/11 truthers, however, say that the collapse was "at or near free fall", from which they infer that the support columns must have been cut by explosives on every storey before the descending mass reached that level. This is one of their big proof points for "controlled demolition". But their data is/are faulty.
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