Re: New AP Physics Convention in Thermodynamics

["QUIST, OREN" <OREN_QUIST@SDSTATE.EDU>]

But, there is no "dot product" in the P dV term cause P and dV are not a
vectors.

Oren Quist

-----Original Message-----
From: Jeff Weitz [mailto:weitz@PIPELINE.COM]
Sent: Tuesday, July 03, 2001 10:07 AM
To: PHYS-L@lists.nau.edu
Subject: Re: New AP Physics Convention in Thermodynamics


Oren, I don't know.  Maybe we could speak of the pressure as the pressure
exerted on the gas instead of the pressure exerted by the gas.  Then the dot
product in the work integral will take care of the minus sign and dV can be
positive for an expansion.

I liked it the old way, too.  Do most chemists really make W positive for
work done on a system, as the AP folks say?

Jeff


Oren Quist wrote:

> I see some problems!
>
> For example, is the dV in the work integral (for work done "on" the
system)
> now changed from negative to positive ???  Or vice versa ??
>
> This goes against the standard mathematical dV representing an "increase"
in
> V.
>
> I guess I can live with, and teach, whatever the accepted convention is,
but
> I thought everything fit together kind of nicely the old way.
>
> Oren Quist, SDSU