Re: [Phys-l] T dS versus dQ

[Bernard Cleyet <bernardcleyet@redshift.com>]

This method is not, I think, very practical, i.e. expensive, very time consuming, etc.

Could one substitute a heating element instead of the speaker?  Very easy to measure the E in.

Could the commercial app. at least two members have be insulated and the heating element and a T added inexpensively?


bc intrigued and will to spend some of his very hard earned retirement to purchase that or similar app. for modification, IF reasonably assured of success.

p.s. one prob. students will be suspicious of using two different methods of adding energy?

On 2010, Jan 17, , at 20:11, John Denker wrote:

> There is a piston 
> with weights arranged so that there is initially mechanical 
> as well as thermal equilibrium.  The plan is to add a
> specified amount of energy.
>
> In subcase 3a, we wiggle the piston at high frequency by
> means of a sound transducer.  This adds a little bit of
> energy to the system.  Sooner or later, presumably rather 
> soon, all of the sound is dissipated.  The sound energy 
> causes the gas to expand.  The gas expands at constant 
> pressure as determined by the weights.  In so doing, it 
> does some work against the weights.  This macroscopic 
> mechanical energy-output is strictly less than the sonic 
> energy-input.  We keep doing this, little by little, until 
> the total delta E (sound in minus macroscopic mechanical 
> work out) is equal to the specified delta E required by 
> the statement of the problem.