"The 2nd tower struck, around 18mins after the first, recieved far less damage as the impact was not dead center of the building as was the first.. The 2nd impact was off-center to the right and at an angle to the building. Damaging one corner if you may... Most of the fuel was ejected out of the impact corner resulting in the hugh fireball witnessed by millions... The 2nd tower did not have entire floors consumed in fire as the first did... If you remember watching the 2nd aircraft made a course correction at the last second thereby missing full straight on center impact. Yet, the 2nd tower impacted fell first... "
The second tower was struck much lower. There was much more weight above the damaged supports.
As far as your basic physics... the supports were built to hold up the towers in a static situation, as soon as part began to fall and build momentum, they could not hold at all, let alone a second per floor.