Re: There's work, and then there's work

["Carl E. Mungan" <mungan@USNA.EDU>]

>      a) "microscopic mechanical work" with what we called
>         "frame-specific total work" -- W_tot
>
>      b) "mechanical pseudowork" with what we simply called
>         "pseudowork" -- W_ps
>
>      c) "thermodynamic work" with what we called
>         "system-specific external work" -- w_ext

For what it's worth, I weigh in with Sciamanda, Mallinckrodt, and
Rauber. In particular, I agree that the above are the 3 most
important kinds of work. My preferred names for them are:

(a) particle work
(b) center-of-mass work
(c) thermodynamic work

Note in particular that I reject the loaded names "pseudowork" and "real work."

Also, I agree that (a) is the most conceptually powerful, (b) the
easiest and safest to calculate correctly, and (c) is the most
limited and dangerous. For example, (c) is ill-defined for the usual
problem of a block sliding across a rough table, (b) is trivially
-f*x where f = frictional force and x = distance slid, and (a)
creates plenty of interesting discussion stemming from Bernard and
Sherwood's controversial paper (AJP 52:1001 1984) which should be
required reading for all intro physics instructors. In particular (a)
is not -f*x which usually gets relegated to cryptic footnotes in
physics texts.

And no, I'm not going to get dragged into a flame war again, Carl
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mungan@usna.edu    http://physics.usna.edu/physics/faculty/mungan/