Re: What Flows?

["Richard W. Tarara" <rtarara@saintmarys.edu>]

Let me answer, I'm sure Leigh will as well.  I'll answer from the point of
view of someone who has been teaching introductory physics (to Bio and Chem
majors) and nothing more complex for 16+ years.

I'll assume A and B contain the same monotomic, idea gas, equal amounts but
at different temperatures.

If I look into each box I see that the atoms are in motion, but there is
more motion in A than B.  To quantize that I'll add up .5mv^2 for all the
atoms in each box.  I guess I could have added the absolute values of mv
but someone older and wiser said do the v^2 thing.  I am conditioned to
calling this quantity the kinetic energy of the molecules.  The average
kinetic energy per molecule due to random motion (which is what we have) is
what I've derived to be the definition of Temperature.  The Total kinetic
energy is what I would call the amount of Heat in each container.  Heat is
energy but not all energy is heat--stuck with a dual nomenclature due to
the caloric sidetrack in history.

Now when A and B are placed in contact I watch over time and find that the
motion in A decreases while the motion in B increases.  Eventually, the
total KE in A equals the total KE in B.  Energy has been transferred from A
to B and it took time to do so.  This has all the earmarks of a 'flow' from
A to B.  True no material 'stuff' has moved but there is more 'something'
in B and less 'something' in A now and my everyday experience suggests the
words 'Energy has flowed from A to B' and since I identify this type of
energy (random KE of atoms) as heat then 'Heat has flowed from A to B'. 
Works for me and students who aren't going on to graduate level thermo
courses.   ;-)

BTW:  I would _not_ expunge the coloric theory from our texts for the very
reason that it is a prime example of how far wrong science can go and still
sound reasonable.  This episode in the history of physics/science should
keep us humble enough not to presume that we NOW have the answers!

Rick Tarara

> Leigh, you are waving your hands; it *does* matter what the mechanism is!
If
> you would answer the question, I could show you how it does matter. 
(Inded,
> I think if you would consider the question and answer it, I would not
have
> to show you (:-))  I have already said it in my words (in private
e-mail),
> but it doesn't look like I am making sense to you.  You say it in *your*
words: 
> Consider two adjacent bodies (A and B) with adiabatic walls except for
the
> adjoining wall which is diathermal.  Say the diathermal wall serves only
to
> keep A molecules from entering B and vis versa, but nevertheless A heats
B.
> Or consider piece of steel A and abutting piece B - where A heats B.  How
> might that happen? 
>
> Don't weary, Folks, we'll get this sorted out shortly.
>
>
>
> Jim.Green@Snow.edu