Re: The Rise and Fall of Simple Machines.

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

Dear Teacher:

You are correct in saying that a comparison between the latent
heat and potential energy stored in a spring was first made by me;
it was not you who injected the spring into this dialog. This was
actually a P.S, comment; my entrance into this thread ended with
this paragraph:

> In the spirit of a Carnot diagram (a circle with arrows) a
> simple machine has only two arrows: work in and work out.
> The number of joules going in is slightly smaller than the
> number of joules coming out. No joules would be lost in
> an ideal machine (negligible mass and friction). This is
> not very different from what we have in calorimetry,
> except that here joules represent "heat" and the amount of
> work done is negligible. Thus "conservation of heat" and
> "conservation of work" before the conservation of energy.

I was (wrongly) under the impression that you were responding
to the above and not to the P.S. message. But all this is not
important. The important detail, however, is that I was only
making a qualitative comparison. You pushed me into
something for what I am not ready.

> 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?

The last question was not addressed. Also the "accepting on
faith" concept ,which you introduced a little later, is pending.
You know about my limited background (our h.s. physics
course started only three months ago). Therefore I again beg
you not to "sabotage" this interesting dialog by injecting
physics which i am not familiar. My background in physics
is kinematics, Newton's three laws and calorimetry.

Responding to

> Why did you mention the spring in the first place? I know
> nothing about heated springs and I am sorry I started to make
> bad guesses. The only connection between heat and energy I
> know about is that 4.18 J of work raises the temperature by
> nearly the same amount as 1.00 calorie of heat. "Work is not
> lost, it exists in the form of heat". That is just another way of
> saying what was quoted above.

you wrote:

> > We'll work on that problem some more after we clear up
> >  your initial false premise.

Can we start dealing with this now? I do not consider my
observation that "potential energy of a compressed spring is
like latent heat" to be a false premise. In both cases something
is stored at one time and released later. Simple machines do
not store anything, especially if we assume that there is no
friction and that masses are negligible. Are you ready to
explain why the quoted below statement is wrong?

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

   Let me end in the same way as before.
> Sorry for bringing the initial sentence back again; I really
> want to know what is wrong with it it. Can it be explained
> in my language or should I just accept your criticism and
> wait till I know more physics? Perhaps you are right,
> students should not try to act as scientists; critical thinking
> at my level should be strongly discouraged. Learn what
> others found first and try to be creative later.

Respectfully, H.S.S.