Regardless of what a metal worker might say about the details of cutting steel beams, I have always had this problem with the "collapse" of the wtc
buildings:
If a building falls at a speed close to free-fall, then very little energy is taken away from the collapse to tear the building apart.
If the building must be torn apart, then that energy has to be accounted for. The gravity collapse of the building might supply enough to tear itself
apart, but then in doing so it would slow down the collapse rate.
Given that the buildings fell so quickly, something else seems to be required to explain the utter destruction of those buildings.
You can't have a huge steel and concrete structure fall down at free fall and tear itself apart at the same time. The supply of energy comes from
the falling debris. So,
1) If the falling debris reaches the ground at free-fall speed, then none of its energy was used to tear the building apart. (Meaning that if the
building WAS torn apart, that energy came from somewhere else)
Or,
2) If the building was torn apart by the falling debris, then the debris would spend a lot of its kinetic energy breaking the building up, thereby
slowing its descent to the ground.
You can't have both. You can't have a building that tears itself apart completely AND reaches the ground very fast. If it does so, then the energy
to disassemble the building came from something other than the kinetic energy of the fall.
Either the building collapses slowly and tears itself apart, or collapses quickly and was already in pieces.




