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 25th August 2010, 07:43 AM #621 ergo Illuminator     Join Date: Aug 2010 Posts: 4,339 Originally Posted by excaza Mr. Third Law, please answer the question. You keep insisting physics agrees with you. Show it. Originally Posted by carlitos * A speck of rubble, dropped from z height, will not initiate the collapse of the WTC tower. * A pound of rubble, dropped from z height, will not initiate the collapse of the WTC tower. * X tons of rubble, dropped from z height, will not initiate the collapse of the WTC tower. * Y tons of rubble, dropped from z height, will initiate the collapse of the WTC tower. (Y is assumed to be greater than X in the above) I agree that Y tons of rubble may have the power to crush through or partially destroy a floor or floors below it. Quote: Everyone here reading this can understand my point. At some point, you will reach enough rubble that it would crush the remaining floors of the WTC. You can pretend not to understand, but even you realize that a moon-sized field of rubble, dropped from some height, would crush a skyscraper. I'm not sure even a moon-sized field or mountain of rubble, dropped from a height of 12 feet would entirely crush the WTC. No. If you had it coming down from a higher height, in a steady stream over a long period of time, we would certainly see some major damage. Total collapse? I'm not sure. Quote: Assuming whatever height z, what is your calculation for Y above? How much energy would it need to generate? How much energy did the upper block apply on the floor below it? Why wasn't this enough to initiate collapse? Because the buildings had inherent load-absorbing capacity, like any modern highrise. When force is coming from above, it is referring ultimately through the entire structure. It would take a much greater force, from a much greater height to "crush" the building. Gravity cannot do it, because the building's design prevents it, as do all modern highrise designs. Last edited by ergo; 25th August 2010 at 07:45 AM.