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# Re: force

You have hit upon a very deep question. It is a failing of the Newtonian
agenda, indeed Hertz in the late 19th century attempted to write a
mechanics not using the concept of force because he didn't know what it
was.
I generally identify force in the way you suggested. If you see an
acceleration, then you need to begin thinking about the presence of a
force. If you can't find one, you might begin to think you are in an
accelerated frame. In this sense, force is a cause of unnatural motion,
where by natural motion I mean constant velocity...of which zero velocity
is a possibility.
In the case of the nuclear force...that was a problem for Thomson and
Rutherford. If the atom contains positive and negative charged things,
one has to worry about the possibility of repulsion creating
instability. So Thomson suggests the plum pudding model in which the
charges are shielded and hence repulsion is reduced. Rutherford shows
that the positive charges are all localized in the nucleus, which should
then explode by electrostatic repulsion, but it doesn't. Conclusion,
there must be another attractive force, lets call it a nuclear force.

The problem gets hairy when you consider the gravititional force, or the
electric one, since there is no contact. If I point my finger at a book
and say rise, it doesn't do it, at least so far. Only when I touch the
book can I lift...that is the push pull...but what if I am not in
contact...then what, how does the force "work"? Newton didn't know how
gravity worked in that sense, luckily he was a theist and so could
imagine God acting in a variety of ways, not required direct contact.On

So you see it is not a trivial question...I go with "that which
produces changes in natural motion"

cheers

Tue, 29 Oct 1996 RSecrest@aol.com wrote:

Now that you have presented many suggestions for naming "g", what
improvement would you offer for introducing the concept of force? Most of my
students are high school sophomores whose earlier physical science texts, as
well as many physics texts, describe force as a "push or a pull." Follow
that with a discussion of the four fundamental forces (and the fifth: duct
tape) and you have confusion. A strong nuclear "push or pull"? And, the
students want to know, which of the four fundamental forces is involved when
I "force" a stalled car?

When first introducing force, I prefer the causal approach: if you want to
know what something is, see what it does. But that too is inadequate. I