Re: A "heat" question

["Carl E. Mungan" <mungan@USNA.EDU>]

John Denker wrote:

>  > Heat is the nonadiabatic energy transfer.
>
> Is that meant to be a definition?
>
> It sounds like a really fine definition, until you
> realize that "adiabatic" means literally "no (heat)
> flowing through" so this seems circular.  We need
> an independent definition of adiabatic or an
> independent definition of heat.

I agree sort of. That is, some care is necessary in how one chooses
to set up the basics in a thermo course. But I believe a typical
sequence goes something as follows:

1. introductory topics: definition of system, distinguish macroscopic
from microscopic points of view
2. notions of temperature, thermal equilibrium, adiabatic vs.
diathermal, and hence calorimetric view of heat
3. review of mechanical definition of work, applications to ideal
gas, surface film, paramagnetic solid
4. more formal treatment: W = adiabatic change in U, Q = nonadiabatic
change in U, heat capacity

> I still doubt these ideas [spelled out below] are useful.

Okay. But would it be fair to summarize our views as possible?

You dislike the ideas of bulk energy, pseudowork, etc. from a
*conceptual* point of view. You prefer to frame the concepts in other
terms and to use other methods to solve problems. You don't like them
because they are limited in utility and not "big ideas of physics" so
to speak. You would rather focus on as small and elegant a set of
central ideas as possible. Fair enough.

I on the other hand think they're fine computational tools and don't
really care what Greek terms are used to call them. I try to keep in
mind their limitations and the ease with which they can be
misunderstood. But there is a good number of problems which *I find*
are most easily solved using these ideas. It just seems a shame to
banish them from my toolbox when they can be so darn useful *at
times*. Carl
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mungan@usna.edu    http://physics.usna.edu/physics/faculty/mungan/