Re: why pseudowork (NOT)

[John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>]

On Fri, 29 Oct 1999, Jim Green wrote:

> This seems to me like just so many words.  The _only_ way to increase the
> internal energy of a system is to do either work or heat on the
> system.  (ie delta E = W + Q)  To say things like
>
> > conversion of bulk kinetic energy into internal energy.
>
> is just hand waving.
>
> We have already discussed ad nausium the fact that energy does not
> "move".  The only way to change the bulk kinetic energy is to do work on
> the system.  Why do we have to make such a mystery out of the First Law and
> it's partner The Work/Energy principle.

Jim,

I would be better able to answer your question if I knew which work/energy
theorem you live by, so let me ask you to answer the following question:

A 2 kg block and a 1 kg block head toward each other with equal and
opposite velocities of magnitude 1 m/s.  After colliding, the 2 kg
block is at rest.  How much work was done on the 1 kg block?

John Mallinckrodt      mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm