by Jerry Russell, Ph.D.
The proof. According to the law of gravity, it is
possible to calculate the time it takes for an object to fall a
given distance. The equation is H=(1/2)at2, where H is the height, a
is the acceleration of gravity (10 meters per second squared) and t
is time in seconds.
Plug in the height of the building at 1350 feet
(411 meters) and we get 9 seconds. That is just about the length of
time it took for the very top of the World Trade Center to fall to
the street below. According to all reports, the whole thing was over
in just about ten seconds.
The author has a master's
degree in Engineering from Stanford University, and a Ph.D. in
Psychology from the University of Oregon.