Re: multi-step reasoning

[Joseph Bellina <jbellina@SAINTMARYS.EDU>]

With all do respect, zero pressure does not exist, and zero pressure
difference is not zero pressure...I can't think of a case in which
changing the volume doesn't involve work being done.

cheers

On Wed, 21 Aug 2002,
John S. Denker wrote:

> Joseph Bellina wrote:
> > ... it seems to me that changing the volume
> > by definition means that work will be done...so I don't know what it
> > means to say "if no work is done"
>
> Work is force dot distance, or in this case P dV.
>
> If the (net) pressure is zero, you can have dV without work.
>
> Please refer to the first example in my previous note:
> the intake stroke of a fireplace bellows.  Arbitrarily
> small pressure difference.  Arbitrarily small work.

Joseph J. Bellina, Jr.               574-284-4662
Associate Professor of Physics
Saint Mary's College
Notre Dame, IN 46556