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

[Diego Saravia <dsa@unsa.edu.ar>]

> > This is not in equilibrium, that was one of mi conditions.
>
> Well, if you exclude the possibility of subsystems with
> different temperatures, then you're not talking about
> thermodynamics.  I don't know what to call it, maybe
> thermostatics or something.
yes, I agree, that is the way Callen call it.



> Every discussion of thermodynamics since (and including)
> Carnot has dealt with multiple subsystems, each with its
> own temperature.  Loosely speaking, one requirement is
> that each subsystem /unto itself/ should be sufficiently
> well-behaved that we can assign a temperature to it.

you can study in thermostatics,  systems with several temperatures, if, the
only way to transfer heat between them is at the same temperature

ok that complex system, will not be in equilibrium, but as it is "designed"
as a reversible one, thermostatics will do the job.

A carnot machine with a working fluid, and two heat repositories, only
transfers heat between systems at the same temperature,

and off course work at the same pressure

 and the displacements are related between subsistems dv and ds, ussualy
equal


if you want to study other kinds of systems you have differents kind of
thermodynamics, as  "finite time thermodinamics" (with its endoreversible
machines), or "irreversible thermodynamics" (with "Onsagerism")