Re: dW turns into dQ

[Jim Green <JMGreen@SISNA.COM>]

> 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?

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 Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen