Re: DW/DW Summary

[Bob Sciamanda <trebor@VELOCITY.NET>]

Vehemently NO for your 7) and 8).

dQ is different for different paths between the same two states.

dQ =TdS ONLY for a reversible path between the two given states.

dS =dQ/T (reversible process) is path independent;

dQ (even for reversible processes {where dQ=Tds} ) is path dependent.

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: Monday, November 01, 1999 9:55 PM
Subject: DW/DW Summary


> . . .
> 7) The only way to calculate DQ for the irreversible process is to
choose a
> reversible process with the same end states as the irreversible one,
> determine the end point entropy of that process and then calculate
DQ=TdS.
> 8) In some cases dS  might be determined from a carefully chosen DQ of
the
> reversible process, but that would be the same DQ for the irreversible
> process and DW would be nil.
>
> Now, Joel, Bob, do we agree with at least the above???
>
> NB I have not used the evil four-lettered word above.
>
> Jim Green
> mailto:JMGreen@sisna.com
> http://users.sisna.com/jmgreen