Re: ENERGY WITH Q PLEASE VOTE

[David Bowman <David_Bowman@GEORGETOWNCOLLEGE.EDU>]

Bob, I said "typically".

Also, when I said that a heating process (i.e. a change in the
system's energy expectation due to a redistribution of its
microstates) is typically associated with a change in its entropy, I
did not mean to suggest the converse that every change in the
system's entropy is also associated with a heating process.  It's
easy to have an entropy change without a heating process.  It's hard
to have a heating process (unless possibly very carefully contrived)
not associated with an entropy change.

David Bowman

-----Original Message-----
From: Bob Sciamanda [mailto:trebor@VELOCITY.NET]
Sent: Monday, November 12, 2001 2:37 PM
To: PHYS-L@lists.nau.edu
Subject: Re: ENERGY WITH Q PLEASE VOTE


Consider that the free expansion (into a vacuum compartment ) of an
isolated gas involves an entropy change with zero "working " or heating"
from the outside.  The state has changed, and so has the entropy, with
no
possible correlation to any "working" on the system.

Entropy is determined by the system state.  Conventially, Working and
Heating refer to
the history of specific processes which (among many other "equivalent"
possibilities) led to that state.

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor
----- Original Message -----
From: "David Bowman" <David_Bowman@GEORGETOWNCOLLEGE.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, November 12, 2001 2:10 PM
Subject: Re: ENERGY WITH Q PLEASE VOTE


> . . .
> 4. I'm for the standard definition of heat given in statistical
> mechanics as the integral of the infinitesimal contribution to the
> differential change in the macroscopic energy expectation due to a
> change in the probability distribution for the system occupying its
> various microscopic states.  Such a change in the macroscopic energy
> expectation will typically be associated with a change in the
> system's entropy resulting from a change in the system's distribution
> of microstates which are accessible to the system's microscopic
> dynamics over the time interval that the changes occur.
> . . .
> David Bowman