Re: Non-conservative forces

[Carl Mungan <mungan@USNA.EDU>]

John Denker wrote:

>  > examples: static friction, tension exerted by
>  > nonstretching strings, etc.
>
> Whoa, lost me there.
>
> 1) Nonstretching spring = contradiction in terms.

That was string, not spring, and indeed the idea I had in mind is
similar to a box which doesn't slide in the back of a truck.

> -- Dissipation has to do with a change in entropy.

Okay.

> -- Non-conservative force has to do with a change in energy.

This seems a bit too vague to me: exactly what kind of energy do you
mean? energy of what, the agent or the object? since "change" can be
either an increase or decrease, it seems to me that lack of change is
also permitted, yes? Conservative forces can store up energy in
potential form; nonconservative forces do not, but I don't see that
requires a loss/gain of energy. I'm reluctant to take a Coriolis
force to be conservative.

> The force is not a function of position.

I would like to add this as a requirement for a force to be conservative. Carl
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
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