Re: Non-conservative forces in a liquid dielectric

[Carl Mungan <mungan@USNA.EDU>]

Pentcho wrote:

> Perhaps I should add something about non-conservative forces.
> Textbooks usually define a
> conservative force as one which, as you do work against it
> (isothermally), keeps the energy
> and does not dissipate it as heat. In contrast, as you do work
> against a non-conservative
> force, the energy is dissipated as heat. Then always friction is
> refered to so that many
> scientists do not suspect that there could be non-conservative
> forces other than friction.

I'm not very happy with these definitions.
I would prefer to replace "heat" with "thermal energy" and take your
3rd sentence as defining a "dissipative" force rather than a
"nonconservative" one.

On the contrary, I would link the idea of "conservative" to
"existence of a potential" as tested by "curl of force is zero" or
less formally, "work is path independent." With this definition, it
is important to realize that a force can be nonconservative without
being dissipative - examples: static friction, tension exerted by
nonstretching strings, etc.

So in striking disagreement with your last sentence, in my view
almost all forces are nonconservative. The *only* common exceptions
are gravitational, Hookean spring, and electrostatic forces. Carl
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mailto:mungan@usna.edu       http://usna.edu/Users/physics/mungan/