Hi Sizzler,
Kuttler makes some very questionable statements and assumptions on the way to a 25-second calculated collapse time.
The concrete was not crushed to dust as Kuttler states. The dust that was ejected in clouds during the collapse was composed primarily of crushed drywall, not concrete. So, where did the concrete go? Most of it stayed in the falling mass and in the debris pile, crushed into various sized fragments. Some of that crushing probably happened when the debris hit the ground; that is, not all of the energy that crushed the concrete was expended above the ground where its loss would have slowed the collapse. The collapse slowed to zero (that is, expended all its remaining kinetic energy) when the debris hit the ground, and that's most likely when a lot of the crushing of the debris, including the concrete, took place.
Kuttler's reasoning (I'm not checking his calculations; that's something that peer reviewers are supposed to do, and if you don't trust the peer reviewers at j911studies to do so, you should contact them with your concerns) is reasonable through the "floating floor" model portion of the letter. However, shortly after that, he starts going wrong in a big way:
Consider a collision between the solid material from the conglomeration of falling floors with floor j − 1. It is only necessary to consider the solid material above this floor because the dust and other ejected material is either suspended in air or has been thrown out of the way and does not contribute to the collision.
Thus, the crushed material disappears from Kuttler's calculations,
whether it has been ejected or not, due to the silly idea that it would be "suspended in air." The entire upper portion of a huge building smashes down upon an acre-sized concrete floor, supposedly crushing it to dust. Where is the air that the dust is supposed to now be suspended in? Ejected fine material would be suspended in air, sure, but not much of the concrete was ejected, and it wasn't crushed to dust in the first place. So the mass is still there, and it's not floating in air, it's entrained in the downward-moving flow of the falling mass, and its mass and momentum still count!
Things really get absurd when Kuttler adds k and r into his model. Kuttler calculates a fraction of the
entire falling mass (which varies in proportion to the kinetic energy of the mass, based on a proportionality constant k) is ejected and/or crushed at each floor. Note that this implies that if the collapse got going fast enough or accumulated enough falling mass, the total falling mass would start decreasing. In other words, he's building negative feedback on the collapse speed into his model with no justification that those phenomena actually existed. (All this is based on his original false notions that (a) most of the concrete turns to fine dust, and (b) the dust that is not ejected has no effective weight.) He then adjusts k until the model shows an arbitrary fraction of "solid mass" remaining after the collapse, and both his k and the fraction of the mass remaining after the collapse keep changing subsequently as he adds other elements to the model. This makes no logical sense.
Respectfully,
Myriad
