Senior research scientist F.R. Greining's report on WTC (Twin towers)

[I FLY IFR]

If the farthest you ever got in math was basic algebra, don't bother reading or trying to understand it.

http://www.911myths.com/WTCREPORT.pdf

Excerpt

7.0 CONCLUSIONS
- An analysis of the energetics of the WTC collapse events has shown that the kinetic energy of the aircraft collisions and the subsequent gravitational energy released by the descending blocks of floors were quite sufficient to destroy the twin towers in the manner observed. The use of explosive devices in either of the two towers is not necessary to explain the collapse events and is considered to be highly unlikely.

- The times calculated for the collapse of WTC 1 and WTC 2 show good agreement with the observed collapse times verifying the basic assumptions of the momentum transfer model used in the calculations.

- The calculated times represent the minimum theoretical times of building collapse. If shorter times are to be physically achieved they must involve an unknown additional source of energy acting in a downward direction. Such a source of energy does not appear to have been involved in the collapse of the twin towers.

- The kinetic energy of the collapse events was sufficient to crush the WTC floor concrete in both towers to particles 100 m in diameter, or smaller, which is consistent with the observed WTC debris particle size distribution.

- From a consideration of the strength of the WTC columns, and the effective area of support they provided, it is demonstrated that the conditions necessary for the initial floor collapse were initiated by the aircraft impact and made irrevocable by the subsequent eccentric loading of the core columns. It is therefore suggested that the total collapse of both towers would have occurred even without the jet fuel fires.