Re: [Phys-L] let's define energy

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

2015-09-26 9:21 GMT-03:00 John Denker <jsd@av8n.com>:

> I agree with the idea, but I would add that the path does
> not have to be adiabatic.
but, if you dont have an adiabatic path, how can you stablish internal
energy?

using an adiabatic wall is circular way of defining heat, because is the
way you say "not heat", but I do not see other way.

In fact if you follow Truesdell Bharatha/Classical Thermodynamics as a
Theory of Heat Engines, you will see that he works with
V(t) volume, Theta(t) temperature, p(t) pressure, Q(t) heating as primitive
concepts.  pp vii

Truesdell thermo is interesting because he dont like to speak about
cuasistatic process, and tries to build a time based thermoDYMANICS, for
using it in fluid mechanics.

I dont have at hand know, but, Bejan in his Advanced Thermo for Eng, shows
how to create a thermo theory from work in one case, or from heat in
another (as if the people of that
thermo were more familiar with heat concepts than from work)

I think I agree with you in that energy  (kinetic) only requires m and vel,
and work needs a little more; a m dx, and newton definition of force, and
you need a non rotational field to integrate

"In particular, if you need a starting-point for your understanding of
energy, perhaps the simplest choice is kinetic energy."

And that remembers me that karlsruhe people have another definition of
heat: entropy.