WTC simple experiment

- collect videos and calculate an average (over the different clips) time t0 of fall of the buildings
- calculate t from y = 0.5gt^2 (y is height of bldng)
- compare those two numbers, the 2nd places a lower bound on the time of fall.

How close does that make the 2nd number to the average obtained from the clips? If the buildings were not demolished expect that the lower bound is not tight at all ie t0 > t. It'd also be relevant to estimate a correction for free fall with air resitance to obtain a tighter bound, though this may be too tricky