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Re: 9-11 Wackos

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On May 25, 2007, at 2:24 PM, Mark E. Deardorff wrote:

"increasing mass and acceleration" To be technically accurate, acceleration does not change. It is constant except that it is immeasurably higher at the foundation than at the penthouse due to its closer proximity to the center of mass of the Earth.
To be really technically accurate the force of gravity doesn't change, but the acceleration does. Prior to impact a floor does not move with the gravity force equilibrated by the support reactions. Since there is no net force, the acceleration is zero. when the falling wreckage strikes the flor the connections break and the combined mass is no longer in equilibrium and accelerates at 32.2 ft/ sec^2. Prior to impact the falling wreckage accelerates at 32.2 ft/ sec^2 except momentarily at impact when an upward force (that required to break all the support connections) exists countering that of gravity, so the impacting wreckage decelerates briefly, since the net force on the wreckage is the gravity force less the connection resistance.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)

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