Re: dW turns into dQ

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

Jim Green wrote in part:

> > To my mind, the Joule mechanical equivalent of heat paddle wheel
> experiment
> > is describing a process where the transfer is dW.  And Joule
> points out
> (by
> > experimental proof) that this process is equivalent to some
> other process
> > where the the transfer is all dQ.  (put the apparatus on the burner
> without
> > turning the crank, and achieve the same temperature rise).  The two
> > different processes that occurred had a definite partitioning.
> ....
>
> > JM & JD (any comments?)
>
>
> Can I join in too?

Absolutely and I'd insist on it.

> In the Joule experiments, it was demonstrated that there is
> an equivalence
> _in raising the temperature_ between a propane torch and a paddle
> wheel.  True enough.  But both processes are irreversible -
> so even though
> the weights and pulleys did work, one is left t odecisde
> whether that work
> should be included in dW or dQ or partitioned between them.
>
> BOTH dQ and dW are work! dQ is NOT necessarily microscopic nor is it
> necessarily due to a temperature difference -- as the Joule
> experiments
> demonstrate. The only consideration is whether the entropy
> changed -- by
> whatever mechanism,  We err in associating Q solely with temperature
> difference or a microscopic process and W with a macroscopic process.

Jim wrote in a related post:

> Yes, Bob, but not quite.  As far as dE goes mox nix.  BUT dQ also >changes
> the entropy!  So it is requisite to at least consider some sort of
> partition between dQ and dW -- surely so in the cases of reversible
> actions.

Jim I'm trying to decide if you are agreeing with me, disagreeing ; or only
partially agreeing.  (I'm trying to make the same decision wrt Bob).

You do seem to say that we have to make some sort of partition in response
to Bob, because of entropy considerations; but you say to me,

> BOTH dQ and dW are work!

I'm guessing that you agree with me, but want to insist on different words.
i.e. you call all of it work, but you distinguish between two types.  One
that affects entropy and you call that dQ and a type that doesn't and you
call that dW.  Furthermore, I think you'd agree that that partitioning is
unique for a *given* process between two equilibrium states.  n'est pas?

Joel