Re: The Rise and Fall of Simple Machines.

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

SOCRATIC DIALOG, PRETENDING TO BE A STUDENT.

Replying to what is below,

> > A simple machine used to compress a spring corresponds to
> > a calorimetric setup in which "latent heat" is accumulated,
> > perhaps in a solar house for subsequent release. Thus energy
> > (mechanical or thermal) can be said to be "work done on a
> > system" or "heat supplied to it".
> >
> > Such generalization may surface naturally in a Socratic
> > postlab dialog. Should we immediately say NO, NO, NO?
> > How should the dialog continue to correct the misconception?
> > I will be happy to play the role of a student, if somebody
> > takes on the role of a teacher.

my high school teacher wrote:

> OK. I would ask the student to explain to me how he would
> compress a spring by heating the system, expecting that he
> would contrive some sort of engine to do so. I would then
> ask him if he had stored all of the heat in the spring. &c.
> He should soon see the error of the parallelism he has
> drawn between latent heat and a compressed spring.

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Your question should not be answered by me, dear teacher.
I did not say it is possible to compress a spring by heating it.
I know it becomes a little longer but it is not compressed,
unless we prevent it from becoming longer. Perhaps we
can heat the spring without heating "walls" (to keep its
length constant). If we do this we have another illustration
of the idea that:

> .. energy (mechanical or thermal) can be said to be
> "work done on a system" or "heat supplied to it".

We heat the system and its potential energy is increased.
The only energies we learned about so far are kinetic and
potential. I am saying that work and heat can perhaps also
be called forms of energy. You are implying that this is
wrong. Should I accept this on the basis of your authority
or should I expect a good explanation in terms of what
I know so far?

By the way, I was contemplating a possibility of measuring
(or at least estimating) the amount of heat (caloric, as they
used to say) entering the spring and comparing it with the
amont of potential energy stored. I suspect that the two
would be identical for a spring of negligible mass, provided
no heat is allowed to escape. What do you think?

Submitted respectfully by a high school student, H.S.S.
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