Hi Alea...........
A bowling ball takes 9.5secs to free fall 110 stories through
air before it hits the ground....
The Twin towers took on average 9.25 secs to fall through
the greatest point of resistance.......hundreds of thousands
of tons of steel & concrete.
Obviously we can deduce that the buildings were standing
up with nothing but thin air......
The rate of acceleration due to gravity is log not linear,
a pancake collapse would have taken over 1min 30 sec.......
& leave lots of pancakes at the bottom.