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9-11 free-fall

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Has anyone predicted and measured the fall time of the 9-11 twin towers?

I have listened to a summary of an analysis that concluded that the world trade towers, fell (9/11/01) at the speed of a free falling object. They state that at free-fall speed, the complete decent should conclude in less than 10 seconds. Varying reports timed the fall, ranging from 8.2 to 9.4 seconds.

The lower floors would have had to crush under the falling floors above. This resistance should have slowed the fall. The claim is that the energy absorption would have increased the fall time 3 to 4 times. It was concluded that the simplest solution is that the columns were destroyed, manually as the building fell, like in a controlled demolition.

An asymmetrical airplane crash did result in a perfect vertical fall.

--
David B. Merrick, Structural Engineer


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