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Re: [Phys-L] work versus mechanical transfer of energy



I do not understand the taylor expansion thing. I assume that equation is a
differential equation along a path.

You have U(S,V) and its partial derivatives T and -P

You assume that you have in all points in that path U S V T and P defined,
they are continuos and derivable.

Do you have an example of a irreversible process in that case?



2016-01-06 19:17 GMT-03:00 Carl Mungan <mungan@usna.edu>:

Consider the equation

dE = T dS - P dV [1a]



that equation is only valid for a path complete developed through
equilibrium states and in a reversible process

Why do you say that? This equation is basically a Taylor expansion of a
function. As John Denker has already said, it’s just calculus.
Reversibility does not enter into it *unless* you try to equate TdS with
“heat” and -PdV with “work” which is a different ball of wax altogether.

-----
Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9b, 572C Holloway Rd, Annapolis MD 21402-1363
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/

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--
Diego Saravia
Diego.Saravia@gmail.com
NO FUNCIONA->dsa@unsa.edu.ar

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