Re: [Phys-l] Temp & Energy density

["Paul Lulai" <plulai@stanthony.k12.mn.us>]

Thanks to all for the help.  I might be "getting it.".

I now understand what Donald helped me understand what Jack was  
stating with (the rough paraphrase) 'you are incorrectly applying  
macroscopic princilples to the setting.'. I needed to be hit in the  
face with it thanks for the wakeup smack Donald.
Thanks to David for going point by point through the energy density  
and ideal gas law situations.
Thanks to John for the initial clarification.
Thanks to Jack for pointing me in directions I need to go.
Thanks to Denker for reminding me
1- I need to study entropy more.
2- my birthday came and went without a copy of Feynman so I must  
simply stop by amazon.com on my way home.

I appreciate the help and patience.

Paul



Sent from my iPod so I can blame Apple for my typos.

Paul Lulai
St. Anthony Village Senior High
Http://prettygoodphysics.wikispaces.com
US First RoboHuskie Team 2574


On Aug 4, 2009, at 4:57 PM, "Jack Uretsky" <jlu@hep.anl.gov> wrote:

> Hi all-
>  Let me try again:
>  There is a thermodynamics of few-particle systems, recognized,
> apparently, by chemists.  Instead of letting the particle number grow
> without bound, one considerslarge assemblages of few-particle systems.
> See Hill, T.,  J. of Chem. Phys. 36 (1962) 3182 and textbooks by the  
> same
> author. One then considers averages over the assemblge.
>                  Regards,
>                      Jack
> "Trust me.  I have a lot of experience at this."
>      General Custer's unremembered message to his men,
>      just before leading them into the Little Big Horn Valley
>
>
>
>
> On Tue, 4 Aug 2009, Brian Whatcott wrote:
>
> > Donald Smith wrote:
> > > Greetings,
> > >
> > > Isn't the volume in question the volume occupied by the gas, not  
> > > the volume of
> > > the chamber?  As others have said, by having just a few molecules,  
> > > you're not in
> > > a thermodynamic situation any more, and these two concepts are no  
> > > longer the
> > > same thing.  By moving the piston when no molecules are hitting  
> > > it, you are not
> > > changing the volume of space occupied by the gas.   Ultimately, I  
> > > agree with the
> > > other posters -- you're applying macroscopic concepts like  
> > > pressure, temperature
> > > and volume to a system where they don't apply.  Hence, the  
> > > paradoxes.
> > >
> > > Yours,
> > It will not be the first time that people have tortured themselves  
> > with
> > conditions
> > that seem almost plausible... but how long  would a piston take to  
> > move as
> > specified without touching a molecule  if just ONE molecule were
> > contained in
> > a container of dimensions ~ 0.1 meter at room temperature?
> > If one could not move quite that fast, how much kinetic energy
> > would be gained by just one collision with a piston?
> > Would you count this as a static or equilibrium collision??
> >
> > Brian W
> > _______________________________________________
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