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HEAT1=HEAT2 ?



On Wed, 27 Aug 1997 Leigh Palmer <palmer@sfu.ca> wrote:

... Describing heat as a form of energy is certainly a gratuitous error
in a textbook. There is no good reason that piece of misinformation
should ever appear in a physics textbook. Who, pray tell, is valuably
informed by such a description? Is work, too, a "form of energy"?
Why could one not describe heating and working as processes by means
of which the energy of a system may be changed? Rather than introducing
ideas that are wrong in the context of physics, why not introduce correct
ideas?

Who wants to change the ideas? It is only a matter of naming things. The
concept of internal energy, and the idea that it can be changed by one of
two processes, heating and working (dE=Q+W), is well understood. Nobody
wants to change these concepts.

Note that dE on the left side is a noun (an energy incement). Therefore Q
and W must also be nouns. Unfortunately, Q was named "heat" when the same
name was already used for what we prefer to call "internal" or "thermal"
energy. For whose sake should this avoidable mental trap be tolerated?

... all I have said presumes that a suitable foundation for the
statements has been laid by introducing the concept of energy before
anything at all is said about heat. I suspect that too little attention
is usually paid to this preparation to make possible the understanding
of what heating is for the great majority of students.

I agree. But this is a new teritory. A small group of high school teachers,
from the modelling workshop in Tempe, Arizona, is currently developping
a curriculum unit based on the "energy before heat" idea. As a workshop
participant (but not a member of that group) I will be informed about the
progress. And I promis to share what I learn.
Ludwik Kowalski
P.S.
The issue of using the word "heat" for two different quantities will
not disappear. We must deal with it without waiting for new teaching
sequences to be developed. I repeat, we have three options: doing nothing,
renaming Q in elementary physics or renaming Q in thermodynamics. In my
opinion avoiding the words "heat and work", as suggested by Leigh, means
doing nothing about the status quo. Why should our mental energy be spent
on a battle which can not be won? We naturally need nouns for Q and W.
What do you think? It is our physics!