Re: pushing vs. pulling

[David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>]

Regarding John D.'s response to John M.'s stated ambiguity about possible
precise meanings for the terms 'push' & 'pull':

> > So what distinguishes a push from a pull?
> ...
> > Is it where the "agent" is located?
>
> No.
>
> > Or is it that "pushes cause compression" and "pulls cause tension"?
>
> That's what I would have said.
>
> > Fortunately, it is seldom if ever a useful distinction anyway.
>
> I disagree.

Upon my initial reading John M.'s original explication of the ambiguity
of meaning, my first gut reaction was the same as that of John D. above.
But a little further consideration caused me to come to the opposite
conclusion.  It seems to me that the most usual distinction between the
concepts of a 'push' and a 'pull' *does* seem to be in terms of where the
"agent" responsible for the force is located.  In case anyone is
interested, I think a 'push' is a repulsive force away from the "agent"
and a 'pull' is an attractive force toward the "agent".  It seems that
the identification of 'pushes' and 'pulls' with compressions and tensions
is less often the actual case when these terms ('push' & 'pull') are
typically used in practice.  I have my reasons for this opinion, but I
leave them unstated here (unless someone challenges me to make a case for
that preference) because I agree with John M. that "Fortunately, it is
seldom if ever a useful distinction anyway".

BTW, I do think that whichever choice is made in defining the
precise meaning of 'push' & 'pull', that there are multiple common
kinds of forces that are of neither category (shear forces, friction
forces, magnetic forces, dipole-dipole & other tensor forces, etc.).

David Bowman
David_Bowman@georgetowncollege.edu