Reply #18: Easy.

[AtheistCrusader]

Each floor weighed approximately 3.2 million pounds. Lets say 25 floors at the top started moving 15 feet down as floor 75 collapsed. You now have 80 million pounds moving down, lets be generous and say half the speed of gravity. You now have an 80 ton wrecking ball, that only gets bigger as it adds each pulverized floor to it's mass on the way down.


WTC 7 didn't fall symmetrically. The non-load bearing, non-structural exterior shell fell semi-symmetrically. WTC 7 was a cantilever frame type building. The exterior walls didn't bear the mass of the building, as WTC 1 and 2 did. The walls are 'hung' on the building like drapes. The best visual indicator is the roofline equipment falling in. At that point, the collapse is well under way, and is clearly not symmetrical, as one end of the equipment vanishes from view before the other. At some point enough of the structural core of the building had collapsed that there wasn't anything left to hold up the weight of the non-structural facade, the shell that looks like the building, and it fell too. The 'building' was long gone when the exterior walls fall. That's why they ripple and twist like a sheet of paper on it's side, on the way down. Because there's nothing to hold it up.