Gang:
I know it's obvious to the members of this group, but it
is not always obvious to others. There can be many
relevant forces in a situation where there are no
accelerations. It is the job of civil engineers and
architects to keep things that way. It is all very well
for us to develop models which rely on "rigid bodies" as
long as we recognize that there aren't any rigid bodies.
All structural materials have limits to the stresses they
can tolerate without failing. Another way of saying this
is to say that sometimes it is not just the vector sum of
the force (that produces the acceleration) that is
important in a physical situation. WBN
Barlow Newbolt
Department of Physics and Engineering
Washington and Lee University
Lexington, VA 24450
Young man if I could remember the names of all of
these particles I would have become a botanist
Enrico Fermi
Telephone and Phone Mail: 540-463-8881
Fax: 540-463-8884
e-mail: NewboltW@madison.acad.wlu.edu