Re: [Phys-l] T dS versus dQ

["LaMontagne, Bob" <RLAMONT@providence.edu>]

Correct - it is not directly relevant. Pasco sells a syringe that has a pressure and temperature sensor inside. The air in the syringe can easily be compressed rapidly and one does get close to the adiabatic P-T relationship. The temperature probe has about a 1 sec response time - which, as WC Maddox has pointed out, is enough time to have some thermal leakage.

Bob at PC

> -----Original Message-----
> From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> bounces@carnot.physics.buffalo.edu] On Behalf Of Philip Keller
> Sent: Friday, January 15, 2010 12:03 PM
> To: 'Forum for Physics Educators'
> Subject: Re: [Phys-l] T dS versus dQ
>
> I still don't see how this experiment is relevant to the question at
> hand:  the question was (I thought) whether fast or slow made a
> difference in the final temperature for an insulated piston.  But this
> device is clearly not insulated, so it seems to me that the apparatus
> demonstrates that a quick compression, happening fast enough to be
> modeled as adiabatic, causes a temperature increase, where a slow one
> remains at the same temp.  [Do we then say that the work in equals the
> heat out?  I know my textbook says that...]  This is an interesting
> demo, but the original question is not being tested.
>
> > -----Original Message-----
> > From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> > bounces@carnot.physics.buffalo.edu] On Behalf Of LaMontagne, Bob
> > Sent: Friday, January 15, 2010 11:53 AM
> > To: Forum for Physics Educators
> > Subject: Re: [Phys-l] T dS versus dQ
> >
> > I'll go back and try that on one. We have a dozen setups and I always
> thought
> > the stiffness was a "feature" to keep everything isothermal  :-)
> >
> > Bob at PC
> >
> > > -----Original Message-----
> > > From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> > > bounces@carnot.physics.buffalo.edu] On Behalf Of Bernard Cleyet
> > > Sent: Friday, January 15, 2010 2:26 AM
> > > To: Forum for Physics Educators
> > > Subject: Re: [Phys-l] T dS versus dQ
> > >
> > > Have you tried grease?
> > >
> > > I'd replace the shaft w/ an unthreaded one and add a sleeve to the
> top
> > > plate, so one may even do "mixing" in addition to quasi-adiabatic
> > > compression (rarefaction).
> > >
> > >
> > >
> > > On 2010, Jan 14, , at 21:03, LaMontagne, Bob wrote:
> > >
> > > > Maybe ours are just stiffer than yours to turn.
> > >
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