Dave of United States wrote:
This is an excellent article. As an engineer here in the US, when I first saw the buildings collapse on TV, I also noted how quickly they fell. In high school, in our AP Physics exam, the one problem I always remembered as an easy one to finish quickly was:

Determine the time and final speed it takes for a ball to fall from a building 500 meters high, disregarding air resistance.

My favorite equation to start that one with? mgh = 1/2 mv^2

I studied like hell for that exam, and passed with flying colors. So, can anyone tell me how the people who support the pancake theory (BWahahaha!) an engineer in MIT, and several others, would've fared on the exam? In the words of my high school physics teacher, an indian from IIT in India, "I FAIL YOU!"

Excellent article. I think this should become a standard problem on every AP Physics exam.

Determine the time it takes for a ball to fall from 413 meters, determine the energy and momentum for 10 floors falling and impacting on each other, determine time for those said 10 floors to collapse, and then show em a video clip of the WTC collapse.