Still no time to watch videos and by no means my final response to those who will attack the opinions of others based on sketchy youtube videos, but the laws of physics are being touted as proof of a cover-up , so here are a few things to consider starting with an aspiring engineer's comments :
"This is a response to the discussions and comments by many suggesting that the planes at the WTC couldn't have brought the buildings down. I'm sorry for being so forward, but in my opinion this is a ridiculous discussion. I am a junior at an engineering-exclusive school studying materials engineering. I admit that I am not an "expert" on the subject. However, I do know enough to explain this situation. The actual maximum burning temperature of a Jet-A fuel (standard jet fuel type in U.S.) is 980 deg. Celsius. If you refer to the Iron-Iron Carbide phase diagram, the temperature at which steel changes from cementite and pearlite (strong phases of steel) to austenite (significantly less strong) is 702.5 deg. Celsius. Also, if a steel structure is exposed to a temperature just below or at the eutectic (702.5 deg.) for a period of time, (*spheroditeis) formed (very weak). All it would take is a few I-beams to lose their structural integrity before the "chain reaction" would start. I don't have a strong opinion on the conspiracy theory, but when people say that the heat from burning jet fuel cannot melt steel it bothers me. It doesn't have to "melt" for it to become ineffective. Also, "very strong type of steel" is the most relative statement ever. The steel used in sky scrapers is a standard carbon steel, not heavily alloyed. In any case, the iron-iron carbide phase diagram describes all carbon steels very accurately. Also, when the buildings actually collapsed, all that potential energy was released into heat and sound, which is true for all destructive reactions. So it is quite possible that after the buildings fell, the temperature of the rubble reached levels higher than any fire could produce."
Source:
http://worldaerodata.com/forum/read.php?5,493
What else was in the building? I assume cleaning chemicals on every floor if not every office? What was the jet carrying for cargo? Plastic, wood, fiber, paint etc. found in an office won't burn hot enough to melt steel, but soaked with a fuel that will would certainly raise the temperature at which their flames reach.
Physics? The buildings fell "down". That's a property of gravity as taught in school, so which laws of physics were violated by fire weakening steel? I'm sorry if its covered in a video I can't see, so just give me one as it applies to the collapse of the two towers that were hit by jets so I can look at it.
Forget tower 7, that one still reeks of foul play to me. Forget insurance claims, which Bush worked there, foreign objects on the bottom of jets (that could have been placed inside) and all the other clutter, just tell me what caused the Twins to fall and be prepared to back it up with something more than a video.