Reply #14: Dust and kinetic energy... [View All]

[Carefulplease]

c-prog, consider the fact that the considerable theoretic kinetic energy of the concrete was unavailable to the collapse. The concrete was turned to dust before it hit the ground. There was no concrete after the collapse, only dust spread over lower Manhattan 2 inches thick.

Even if all the concrete had been turned to fine dust during the progression of the collapse, that would not have slowed it down one bit. One pound of crushed concrete still weight one pound. Only what gets ejected outside of the footprint does not contribute further to the collapse. There is no evidence that most of the concrete got ejected that way.

During the early stage of the collapse it is mostly smoke from the burning floors and then dust from crushed gypsum wallboard that would have been ejected. The bulk of the energy available to crush much concrete into fine dust was released in the late stage of the collapse when the falling stack of floors hit the ground.

Even if just 10% of the concrete had been dispersed in the form of fine dust during the early stage of the collapse (to say nothing of the other materials), that would still account for a layer of dense dust with an average thickness of one inch covering a *net* area of more than 90 acres (the area of 68 football fields) in lower Manhattan.

Concrete just accounts for a fraction of the weight of the towers anyway.