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RE: 9-11 Wackos

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"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.
 
Mark E. Deardorff, S.E.
Structural Engineer
Burkett & Wong Engineers
3434 4th Ave
San Diego, CA 92103
P 619.299.5550
F 619.299.9934
mdeardorff(--nospam--at)burkett-wong.com
 


From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)gmail.com]
Sent: Friday, May 25, 2007 12:13 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: 9-11 Wackos

Exactly.

And remember, the resistance strength at each floor is constant. So as you go down the building, each floor has the same capacity to resist the pancacking, but the force cannot be overcome due to the ever increasing mass and acceleration to the point that it becomes neglible to momentarily slow down the fall.

-g

On 5/25/07, Christopher Wright <chrisw(--nospam--at)skypoint.com> wrote:

> Maybe I just don't get it but, in my mind, when an object in motion
> meets a stationary object, there is a lose of momentum thereby
> slowing down the acceleration process.
Momentum is conserved in a collision, although energy may be
dissipated. If you think of each floor as a rigid body, the force of
impact acts to speed up the lower floor and slow down in upper floor,
such the mu1Vu1 = ml1Vl2+mu2Vu2. The upper floor will have to slow
down a little bit momentarily becasue it is subject to the reaction
of the force needed to break the support connections for the lower
floor.

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



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--
-gm