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Re: macroscopic vs microscopic degrees of freedom

At 10:30 AM 31-10-99 -0800, you wrote:
On Sun, 31 Oct 1999, Rick Tarara wrote:

> > > James Prescott Joule operated his paddle-wheel and called the long-term
> > > result heat. Lots of other people do the same.

Well, yes , in his paper he referred to the "mechanical equivalent of
heat" -- Had he said "heating" or referred to an action of some sort -- as
in "doing heat" -- like doing work -- I would agree.

The fact is that the paddle wheel and a propane torch do essentially the
same thing -- they both increase the entropy and they both increase the
internal energy -- and hence the temperature.

In deed, the only mechanism I am sure of that does NOT change the entropy
is the reversible piston in a cylinder --- the ONLY classical action which
goes in the W of the First Law. The paddle wheel does not -- but the point
is somewhat moot -- everything real is irreversible and hence goes into W
or Q willy nilly -- ie one can not calculate the macroscopic work done by
one's hand on the paddle wheel and call it W or Q with accuracy.

I am still thinking about the piezoelectric effect and magnetic
constriction and am hoping to find some others.

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