Beachnut, about your physics: imagine tilting wtc sideways. Then accelerate it with 0,7g for 10 seconds. Tere goes 70 % of your e=mgh. Then pulverize the concrete. That is not possible if you used all the potential energy of the building - concrete does not pulverize more than c. 10% from ground impact -it crumbles to small/big pieces, but not to dust, more than about 10%. Look it up from any gravitational destruction of concrete.
Then try to take down the steel super structure wit gravity. Even with pre weakening, this would take at least 66% of the energy, where bottom 1/3 would need to be exploded, and after that there would be no acceleration, just crushing with constant speed.
...and then you need the power to shoot the building to 200m radius. You have no energy left and no energy working sideways.
In real life there is no gravity driven examples for phenomenon seen with 9/11, even for small parts of it, but plenty of examples for same stuff done with explosives.