John Berry wrote:
Ahuh, and yet no details are ever availible.
That is incorrect. NIST has published thousands of pages of data. Please do not dispute matters of fact.
I'm not questioning if when a floor is pulled if further floors worth of destruction will occur, obviously it will. The question is in a building such as the twin towers or other tall conventional buildings if a floor near the top is pulled if the entire thing will collapse at near freefall speeds.
All other buildings destroyed by this method, on purpose or by accident, have fallen at freefall speeds.
I would expect in the case of the WTC that a lot of it would collapse, but I would think it might stop 2/3rds of the way down . . .
You have that backward. When the floor near the top has enough energy to break the next one down, that adds one floor to the mass of falling material, increasing the total mass that strikes the next floor down. After ten floors collapse you have 10 floors worth of additional mass falling down. This is not quite true, because some of the material falls out the sides and straight down, but most of it joins the total mass of falling material, and adds to the force of the reaction. Two-thirds down you have *far* greater force striking each additional floor, and much greater damage. If anything, it should go faster.
, and at the very least to occur far more slowly than freefall speeds which means that the building offered 0 resistance which is at odds with the conservation of energy.
As Stephen A. Lawrence already pointed out on this forum, the breaking reaction occurs at the speed of sound. A floor either breaks or it does not break within a fraction of a second. The energy absorbed by the breaking is absorbed in that fraction of a second and the reaction continues nearly as quickly as it would in free fall.
You can see from the 9/11 photos -- and from the photos of other buildings deliberately destroyed by this method -- that the speed is a little slower than free fall. Material thrown out the side hits the ground a little sooner than the falling bulk of the building.
- Jed
