Re: Structural failure of NY's WTC

["Prof. John P. Ertel (wizard)" <jpe@USNA.EDU>]

It is of course not difficult to imagine why intense heat might cause the
upper floors to collapse.

A very good clue to the "progressive" failure of the rest of the structure
is the description of the one man that "road the building down."  He talks
about the floor below him collapsing and then there is a "bump" when it
hits the floor below.  Then there is another brief period of falling and
another bump.  And so on it goes.  This man has come to be known as "Mr.
82nd floor" (or 83rd depending from which station you hear the story).

In any case, we seem to be faced with a "cascading collapse" rather than a
spontaneous (simultaneous collapse) of the structure.  Well this is just
the topic we are currently covering in Physics all across the would as
we study "1st Term Mechanics" --- NEWTON"S LAW OF INERTIA.

While each floor may well be able to withstand the weigh of all of the
floors above it.  It seems that none of our buildings are able to
withstand both that weight and the impact of many tons of material
slamming down from above.

Well this seems an excellent opportunity to show the importance of
inertia.


+=================================+

On Sun, 16 Sep 2001, Tucker Hiatt wrote:

> > Moral astonishment aside, I was completely taken by surprise upon
> > observing the physics of collapse of the World Trade Center
> > buildings.   Reading reports such as
> > <http://abcnews.go.com/sections/scitech/DailyNews/WTC_towers_structure010911.html>
> > has helped very little.
> >
> > Would any PHYS-Ler care to speculate regarding why a structural
> > failure (due to intense heat) at or above mid-section would lead to a
> > domino-like structural failure all the way down?  Clearly, many
> > experts in structural integrity were surprised when the collapses
> > occurred -- some of those experts were rescue workers toiling
> > underneath the doomed buildings.
> >
> > - Tucker
> > --
> > ***********************************
> > Tucker Hiatt, Director
> > Wonderfest
> > P.O. Box 887
> > (39 Fernhill Avenue)
> > Ross, CA  94957
> > hiattu00@usfca.edu
> > 415-577-1126 (voice)
> > 415-454-2535 (fax)
> > http://www.wonderfest.org
> >
> > Truth is a great flirt.  - Franz Liszt
> > ***********************************

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