Ok, I'll try to explain the 'freefall' bit.
Suppose for the the purpose of the argument that one floor collapses, the floor underneath would take the force of the falling debris, if it is going to collapse too, it will collapse as soon as the debris hits it as that is the point of maximum force.
Same goes for the floor below, and below that and below that and so on.
It is an inelastic collision and the mass above sticks together so each floor below is impacted with greater and greater force.
This means that the time for the floor below to collapse will keep reducing.
So near freefall speed is not only not a surprise but completely EXPECTED if a building collapses.
That means you can stop widening your eyes and screaming 'freefall' as if it is some kind of smoking gun.
If this is resolved to your satisfaction (specificall the near free fall speed) we can move on to the next aspect of the collapse which makes you believe it was a controlled demolition.
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