Speed of Fall
Twin Towers' Rates of Fall Proves Demolition
Each of the Twin Towers fell completely in intervals of time similar to that taken for a block of wood dropped from a tower's roof to reach the ground. A block of wood has about the same average density as the main components of the towers near their tops.
In a vacuum, a block of wood (or lead) would take 9.2 seconds to fall from the tower's roof. In the air a block of wood, say ten inches on a side, might take 50 percent longer than in a vacuum. Fifteen seconds, a good estimate for the total time of collapse of the North Tower, is about the time it would take our block to fall from the roof. The rubble from the Tower probably had similar average density to our block of wood, since the floor slabs consisted of corrugated sheet metal and lightweight concrete, and the perimeter steel columns were hollow with walls only 1/4th inch thick at the Towers' tops. Air resistance alone could account for the slowing of the falls to the point where each Tower took about 15 seconds to completely come down.
The official story requires that more than air resistance was slowing the descents. The falling rubble would be having to crush every story below the crash zone -- ripping apart the steel grids of the outer walls and obliterating the steel lattice of the core structure. The resistance of the intact building itself would be thousands of times greater than air resistance.
If air resistance is able to increase total collapse times by even 20 percent, then shouldn't the addition of the resistance of the buildings themselves increase the time several thousand percent, to at least tens of minutes?
Of course the idea of a collapse lasting minutes is absurd. So is the idea of a steel frame building crushing itself.