Posted on 11/18/2005 11:40:33 AM PST by Iconoclast2
I agree. The NIST report makes the point that they were 90% empty space, and could easily collapse on themselves. The suspicious points to me include WTC7, the recent purchase by Silverstein, Silverstein's "pull it" remark, molten metal in the bases, and the fact that when they went to remove the gold in the basement, someone had already been there trying to break in!
How could somebody possibly have been digging around in the gold storage area without being noticed?
Ah! Here come the "experts"
The amount of gravitational energy unleashed when the Twin Towers fell was on the order of a small nuke. I forget what power-of-ten joules I calculated, but it was pretty darned huge. All that energy all had to get converted to some other form, and an awful lot of it got turned into heat.
It takes an awful lot of energy to pulverize that much concrete and other materials into a pyroclastic cloud. I doubt much kinetic energy turned into heat.
Where do you think it went?
Pulverizing the concrete into dust. If you compare the wreckage of WTC with other buildings hit by planes, the debris is much, much finer.
I don't think the dust has a higher energy state than the unpulverized concrete. Imparting that mechanical energy may have the effect that the concrete gets pulverized, but I don't think pulverizing in and of itself absorbs energy except insofar as it turns the energy into heat.
The point is that it takes energy to pulverize the concrete. Every joule of kinetic energy that goes into making powder is a joule that cannot be converted into heat.
Does pulverizing concrete result in any chemical or state change for its constituents? I thought it just resulted in physical rearrangement, much like sanding down a block of wood. And sanding, sawing, drilling, etc. all produce lots of heat.
I don't think there's any state change. The change is at the physical level. Physical kinetic energy is absorbed in the process of pulverization. Presumably some heat was produced in the reaction as well. I have not seen any competent calculation that would compare the amount of heat produced to the amount of energy absorbed in pulverization. It is a very interesting question.
In the absense of any chemical or state change, the calculation is very simple: any energy that goes in that does not come out (as sound, vibrations, or whatever) is converted into heat.
If I break a rock with a hammer, the hammer stops, but the rock does not get hot. I don't think all the hammer's energy can be found in the momentum of the resulting pieces.
It takes a lot of mechanical energy to produce a small amount of heat, and vice versa. Dropping a ten-pound hammer three feet would, if all of that energy were converted into heat, represent enough heat to increase the temperature of one gram of water by about 10°C. A quick google search suggests that stone has a thermal mass about a fifth that of water. Distributing 100% of the impact energy through 50 grams of stone (concentrating the energy in about 1/10lb) would heat it by about 1°C. I would hardly expect the stone to "get hot" from one such impact. There's just not enough energy there. By contrast, the collapse of the world trade centers represented a release of energy comparable to a small atomic bomb. Even if only a small portion of the energy got converted to heat within the building materials (a lot would get converted into heat in the ground or in the air) that would still represent a really incredibly huge amount of heat. Depending upon how the energy got concentrated, it should not be surprising if parts of the building would get very hot from mechanically-generated heat alone.
One might expect in the wake of the event that someone might have done a calculation of the amount of heat released, but if so, I have never seen it. I personally doubt that the collapse of a building would release sufficient heat to melt metal, but the WTC collapse is beyond the range of any mechanical energy releases I have had occasion to observe or could confidently opine upon.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.