wrote:

PROPOSITION 2:
A free fall from a height equal to the roof of WTC 7 would take 6
seconds. This proposition derives trivially through (Galilean)
kinematical considerations alone:

Displacement = initial velocity * total time + 1/2 * acceleration *
total time^2

or

s = ut + 1/2at^2
where
s = 174 m (height of building)
u = 0 m/s (building was stationary prior to collapse)
a = 9.8 m/s^2 (since gravitational field strengh averages at
a constant)

Thus,
174 = 0 t + 1/2 9.8 t^2

Solving for t
t = sqrt( 2 * 174 / 9.8)
= 5.9590
~ 6 seconds

Proposition 3:
You're just another discredited 911 conspiracy kook.

But as physics prof Steven Jones and others have mentioned, this is a matter
of physics. If momentum had been conserved, the 47-floor collapse might have
taken 27 vs 6 seconds.

Nick