WTC_7

Witnesses who all worked in the buildings (including the towers) said the lobbies were all blown out and unrecognizable. I want to recommend, if you haven't seen it, the last man in the twin towers is incredibly moving. He was the janitor. I'll try and find a link.

glugglug

The 9.8 m/s is acceleration , not velocity. So your math is wrong, depending on which 2.25 seconds are in question. That said, the minimum free fall distance is the 2.25 seconds of free fall was the first 2.25 seconds of collapse starting from rest is even bigger than you just calculated, instead at least 80 feet minimum that NIST has admitted to.

WTC_7

Correct sir. I'm not sure if this building reached "terminal velocity", but that is what my calc would be based on. Basically, as you said, my value is the minimum.