Re: single-system dQ + dW

[Bob Sciamanda <trebor@VELOCITY.NET>]

At this point I would ask John Denker (or anyone who can) if he would
recommend engineering texts (preferably at the Junior/Senior undergraduate
level) which teach his interpretation of the first law of thermodynamics.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: John S. Denker <jsd@MONMOUTH.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, November 02, 1999 8:03 PM
Subject: Re: single-system dQ + dW


> At 07:03 PM 11/2/99 -0500, Bob Sciamanda wrote:
>
> > 2) JD interprets dE=dQ+dW as a partitioning of energy CHANGES in a
system
> > on the basis of the properties of the final system state: eg., was the
> > energy increment thermalized into "Heat" ("thermal energy") so that it
> > changed the system entropy, or was it Work (with no regard to the
> > mechanism of its entry/exit into/from the system)?
>
> I agree with Bob's summary of my thoughts on this issue.
>
> > Do John Denker's views show a disconnection between (1) academic,
textbook
> > thermodynamics and (2) real-world engineering practices?
>
> That may be an important part of the story, but I would rather not word
it
> quite that way.  For one thing, the word "academic" has many meanings:
> some pejorative, some just the opposite.  So I tend to avoid the word
> except in its most literal meaning, as in "academic institution".
>
> Perhaps a better way to describe it is a disconnection between (1)
> elementary, introductory thermodynamics and (2) real-world no-nonsense
> thermodynamics.
>
> Specifcally, the emphasis on
>         dU = dQ + dW      ** for each system separately **
> (as opposed to the emphasis on transfers from A to B) is important if
> dissipative processes are being considered, and usually not important
> otherwise.
>
> If that's what's going on, it's a pity, because the shortcut provides
> little or no simplification of the elementary case, and does all sorts
of
> mischief in the real-world case.