NITPICKING? Was failure of NY's WTC

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

Tucker Hiatt asked :

>  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?  ...

My spontaneous reply was:

> Without reading anything my answer would be "under the
> weight of what was falling down."

A minute or so later I added:

> IN OTHER WORDS, THE KINETIC ENERGY OF FALLING
> SECTIONS WAS USED TO PERFORM THE DESTRUCTIVE
> WORK OF BENDING AND CRASHING.

Was the qualification necessary? OK, it would be better to replace
the word "weight" by the word "impact". However, the phrase
"under the weight of" would be actually appropriate if by weight
we mean "the force exerted on the supporting structure" instead
of the "mass multiplied by g". In static situations two definitions
are equivalent; in dynamics they are not. Sorry for bringing this
trivial comment; I am doing this now because I remember a
recent thread on "what is weight?"
Ludwik Kowalski
PS
What is obvious to us is not always obvious to students. I will
try to use some comments made under this thread in teaching,
including the escape pipes "proposal". What is good for a
science fiction writer is not good to a real scientist or engineer.