Okay Jazzy, I gave you the figures for a one storey drop, figure out the math for a 2 storey drop, as you seem to be clinging to this theory, though why 2 storeys would just disappear is beyond me. Be interesting to see your work though. Look forward to it
I did it a few years back. I have no record of it now. Not that it's difficult.
Using V^2=U^2+2*G*s, where U=0, G=9.81 meters/sec^2, s=7.34 meters, then V=sqrt(2*9.81*7.34)=12.0 meters/sec, or 26.8 mph.
The assumption of G nowhere near approaches the
actual acceleration at the start of collapse, because the structures actually failed
at some unique point, and had to spread their failure away from that.
One thing we can be sure about is that this point of failure was
not at the dead center of a tower.
Failure (of the lateral support of the floors) from a point
somewhere against its exterior columns would have given the WTC2 tower a moment to lean against, which it did.
Failure (of the lateral support of the floors) from a point
somewhere against its interior columns produced an interesting motion of the central mast of WTC1, but obviously less in the way of lean, with the smaller moment.
That's as far as a calculator will allow me to reach.