Re: Thermodynamics

[Hugh Haskell <hhaskell@MINDSPRING.COM>]

At 21:49 -0400 8/29/01, Justin Parke wrote, asking for comments on
the following:
> "There is no reason to expect that an object will have any one particular
> acceleration given a certain force.  When the acceleration of the object is
> measured, however, we find that it obeys a law of the form a = F/m."
I would say that this would be true only if one has definitions of
both force and mass that do not involve acceleration in any way. I
don't think any exist. In fact, we use the above relationship to
identify forces. If an object is accelerated we infer that a force
must have been acting upon it, and conversely, if a force acts on an
object and it doesn't accelerate, we infer that we have not taken all
the forces into account. If necessary, we "invent" a force to account
for the acceleration (e.g., centrifugal forces, coriolis forces,
gravitational forces). I believe that this relationship has come to
be accepted because of it's success in helping us to identify forces.
Certainly Aristotle didn't accept such a relation. But we now know it
was because he didn't consider some of the effects we now take for
granted as forces, not to be forces (or whatever he called those
things we now call forces, or took them to be).

In a certain sense, quantum mechanics came about because we found a
situation in which we could not figure out how to infer a force in a
situation that was clearly not behaving in the was one would expect,
namely, the arrangement of the proton and electron in the hydrogen
atom. Although the concept of force is not particularly relevant to
quantum mechanics, it is not difficult to show that, some average
form of F=ma arises if we measure expecation values in QM.

Although, NSL is a statement about how nature works, as seen by it's
supplanting by QM in certain realms, it is probably not too far off,
as long as we remain firmly in the arena of large objects, to treat
it as a way to define force (as long as we can all agree on what
"mass" is).

Hugh
--

Hugh Haskell
<mailto://haskell@ncssm.edu>
<mailto://hhaskell@mindspring.com>

(919) 467-7610

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