Re: dS=0

[Bob Sciamanda <trebor@VELOCITY.NET>]

One cannot universally say that "Q things" change the entropy and "W
things" do not - ie; such "things" cannot be uniquely/universally
identified.  Whether, and how much, a system's entropy has changed is
determined by the end states, no matter the mechanism of transition from
one state to another.

IOW the entropy change is not uniquely/universally determined by the dW vs
dQ partition of the actual process.
The entropy change depends on the totality of everything which affects the
state transition: the nature of the system, its equation of state, the
imposed constraints, etc.

Eg: an infinite variety of closed cycle processes are possible (using an
infinite variety of various combinations of Q things and W things), all
resulting in zero entropy change of the system.

Bob


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

----- Original Message -----
From: Jim Green <JMGreen@SISNA.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Friday, January 07, 2000 1:13 PM
Subject: Re: dS=0


>  . . .
> The question on the page is "Why, if both Q-things and W-things are both
> mechanical work, what then is the difference between W and Q if any?"
The
> answer is that Q-things change the entropy and W-things do not . . .