Valt inlägg:
In trying to come to terms with what actually happened during the collapse of the World Trade Towers, the biggest and most obvious problem that I see is the source of the enormous amount of very fine dust that was generated during the collapses. Even early on, when the tops of the buildings have barely started to move, we see this characteristic fine dust mixed with larger chunks of debris being shot out very energetically from the building. During the first few seconds of a gravitational fall nothing is moving very fast, and yet from the outset what appears to be powdered concrete can be seem blowing out to the sides, growing to an immense dust cloud as the collapse progresses.
The floors themselves are quite robust. Each one is 39" thick; the top 4" is a poured concrete slab, with interlocking vertical steel trusses or spandrel members underneath. This steel would absorb a lot of kinetic energy by crumpling as one floor fell onto another, at most pulverizing a small amount of concrete where the narrow edges of the trusses strike the floor below. And yet we see a very fine dust being blown very energetically out to the sides as if the entire mass of concrete about 400,000 cubic yards for the whole building were being converted to dust. Remember too that the tower fell at almost the speed of a gravitational free-fall, meaning that little energy was expended doing anything other than accelerating the floor slabs.
Considering the amount of concrete in a single floor 1 acre x 4" and the chemical bond energy to be overcome in order to reduce it to a fine powder, it appears that a very large energy input would be needed. The only source for this, excluding for now external inputs or explosives, is the gravitational potential energy of the building. Any extraction of this energy for the disaggregation of the concrete would decrease the amount available for conversion to kinetic energy, slowing the speed of the falls. Yet we know that the buildings actually fell in about 9 seconds*, only slightly less than an unimpeded free-fall from the same height. This means that very little of the gravitational energy can have gone toward pulverizing the concrete.
Even beyond the question of the energy needed, what possible mechanism exists for pulverizing these vast sheets of concrete? Remember that dust begins to appear in quantity in the very earliest stages of the collapses, when nothing is moving fast relative to anything else in the structure. How then is reinforced concrete turned into dust and ejected laterally from the building at high speed?
Ett meddelande kommer att skickas till ansvarig som besultar om inlägget skall tas bort, av vilken anledning vill du rapportera det här inlägget?