Wayne Trumpman's analysis of the fall of WTC1 at
http://www.911research.wtc7.net/papers/trumpman/CoreAnalysisFinal.htm has some interesting figures about the excess of kinetic energy from the falling part of the building over the amount needed to disrupt the structure. Despite taking a mass for the tower that is only 40% of the mass given by other references, he still finds enough excess energy in the collapse to pulverize about 25% of the concrete to dust, on average, in the first four floors to collapse - the least energetic part of the collapse. Since other researchers, including Steven Jones, have found that a relatively small proportion of the concrete was pulverised to fine dust, it seems clear - despite Trumpman's attempts to conclude otherwise - that there was ample potential energy in the structure to collapse the steel supports and to produce the quantities of dust observed.
I'd recommend you read Trumpman's paper, as there is a considerable amount of detailed presentation of the calculations in it. It has some major errors - one is to assume that there was no excess of energy in the first collapse of a floor; his argument is based on the fact that the velocity of the falling portion of the building at the time of impact was no less than what would have been expected due to gravitational acceleration, but since at that instant the collision with the floor had not occurred, no discrepancy in velocity would be expected. However, he appears correct in stating that there is an excess of energy over the requirements to collapse the structure.
I'd recommend you also take a look at Frank Greening's articles on the collapse, at
http://www.911myths.com/html/other_contributions.html, which address several aspects of the WTC collapses, with calculations. Greening addresses the rate of collapse in some detail, and explains exactly why a collapse in the observed range of 80-90% of free fall acceleration would be expected. Finally, of course, Bazant and Zhou's paper, at
http://www-math.mit.edu/~bazant/WTC/WTC-asce.pdf, is one any serious student of the collapse should read, being a peer-reviewed analysis of a likely collapse scenario which shows a large excess of energy in the structure over that required for complete collapse.
I think you may be confusing heat (i.e. thermal energy) with temperature here. Hot things cool down unless they are either perfectly insulated or continuously heated. Molten iron is not a heat source. It may be a heat reservoir, but is not in itself producing heat. Also, I didn't say that the lack of insulation ruled out thermite, but that it ruled out thermite
at the time of collapse. The point is that, if indeed there was molten metal under the rubble pile some weeks later, itself debatable as all the accounts can be traced back to a single unattributed eyewitness account, heat must have been generated at a time close to when the observation was made in order for the metal to remain molten. This is feasible for underground fires, which are generating heat continuously. Without such a heat source, metal melted at the time of collapse would cool and solidify. If, however, we accept that a heat source was present in the rubble pile capable of generating sufficiently high temperatures to maintain iron at its melting point, then that same heat source would necessarily be capable of melting iron that was in solid form at the time of the collapse of the towers. In other words, molten metal present some weeks after the collapse doesn't demonstrate the presence of molten metal during or shortly after the collapse, it simply demonstrates the presence of a heat source in the rubble pile.
NIST speculates as to the nature of the yellow hot substance, as does Jones. The colour similarity is a very dubious piece of data, as it relies on comparison of photographs taken in very different lighting conditions and with unknown post-processing having been done. All this is a very long way from proving that the substance is molten iron from a thermite reaction.
There will always be questions - the most well-understood events still contain some areas of uncertainty. What I have found, however, is that the explanations of these issues that are in accordance with the official account of the events of 911 tend to resolve large questions while leaving minor points unexplained, whereas those provided by the truth movement tend to explain minor points by creating enormous questions which are then left unresolved. In the end, it comes down to Occam's Razor for me.
