Articles Using the Speed of the Twin Towers Collapse as Proof of Controlled DemolitionJerry Russel (MS in Engineering):
As your eyes will tell you, the World Trade Center collapses looked like controlled demolitions. Here's the proof.
The proof. According to the law of gravity, it is possible to calculate the time it takes for an object to fall a given distance. The equation is H=(1/2)at2, where H is the height, a is the acceleration of gravity (10 meters per second squared) and t is time in seconds. Plug in the height of the building at 1350 feet (411 meters) and we get 9 seconds. That is just about the length of time it took for the very top of the World Trade Center to fall to the street below. According to all reports, the whole thing was over in just about ten seconds.
It is as if the entire building were falling straight down through thin air. As if the entire solid structure below, the strong part which had not been burned or sliced or harmed in any significant way, just disappeared into nothingness. Yet this (within a small tolerance) is what we would expect to find if there had been a controlled demolition, because the explosions below really do leave the upper stories completely unsupported. Like the Road Runner after he runs off the edge of the cliff, the entire building pauses a moment, then goes straight down.
Any kind of viscous process or friction process should have slowed the whole thing down. Like dropping a lead ball into a vat of molasses, or dropping a feather into the air, gravitational acceleration cannot achieve its full effect if it is fighting any opposing force. In the case of the World Trade Center, the intact building below should have at least braked the fall of the upper stories. This did not happen. There was no measurable friction at all.
This proves controlled demolition.
Here's the other article using the same type of argument.