Re: Thermodynamics essay

["John S. Denker" <jsd@MONMOUTH.COM>]

At 04:00 PM 10/5/01 -0500, RAUBER, JOEL wrote:
> 1) In the discussion John provides four bulleted items for the four possible
> ways energy can leave system A and arrive at system B.   I simply don't see
> that the structure of this equation doesn't allow for the 3rd and 4th
> possibilities; it strikes me that the structure either allows all four ways
> or none.
>
> E.g. 3 units of energy are transfered from system A in thermal form and
> arrive at B in nonthermal form.
>
> Then Delta E = +3 and W = 0 and Q =+3, the structure allowed it.

Nice try.  This indicates an understanding of what repairs are necessary.
But this attempt to repair the W+Q equation violates the usual definition
of Q, namely energy that was thermally transferred from a warmer body to a
cooler body.

It is bad practice to have Q mean one thing on Monday and another thing on
Tuesday.  I don't see how to have a consistent definition of Q that covers
all the cases.  Also note that I've added a fifth bullet, "combinations of
the above", that will be even harder to handle.

I still think that any attempt to repair the W+Q equation will either end
up being so complicated as to be self-defeating, or will end up separating
the conservation law from the thermal/nonthermal classification lemma, as
described in
  http://www.monmouth.com/~jsd/physics/thermo-laws.htm

As it says there:  Dividing the energy itself into a thermal part and a
nonthermal part is much less problematic than trying to divide the
transfers.