Re: Definition of heat [and S]

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

Let me paraphrase JohnD (see below) in order to be corrected,
if necessary.

There are no advantages in emphasizing that heat is "energy in
transfer".  Heat is a form of energy. Thermal energy is heat.
It is not wrong to say that the heat lost by an object A is later
present in objects B or C. The caloric analogy is not totally
wrong. Heat can flow but it is not a material substance.

There are more important issues to deal with; some students
are not aware of the fundamental difference between heat and
temperature. Trying to avoid dS=dQ/T may be challenging to
some creative thinkers but many teachers are used to it. They
need to be persuaded to abandon this macroscopic approach.

Ludwik Kowalski
-----------------------------
John Denker wrote:

> I agree that there is a deplorable lack of agreement as to the definition
> of heat.
>
>   *) The first definition (heat = thermal energy) is/was used by Carnot
> (1824), Boltzmann (1872), Feynman (1963), and every experimental
> physicist I've asked about it (including people with PhDs from
> California, Cornell, Duke, MIT, and Stanford).
>
>   *) The second definition (heat = heatflow) was can be traced as far back as
> Slater (1939;  Dover reprint 1970) and was advocated by Zemansky in his
> 1970 _Physics Teacher_ article.  This definition has made it into a number
> of textbooks and even into the current version of the Encyclopedia Britannica:
>    http://www.britannica.com/bcom/eb/article/6/0,5716,40566+1,00.html
>
>   *) One can dig up additional even-more-unorthodox definitions, but they
> are not worth discussing.

..... [snip snap] .....

> Longer-term recommendation:  The heatflow definition has got to go.
>
> In my judgement
>   -- The technical arguments in its favor are invalid.
>   -- It has no practical advantage when doing thermodynamic calculations.
>   -- It has no pedagogical advantage, and has serious pedagogical
> disadvantages.