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Re: [Phys-l] T dS versus dQ



If you push/pull on the gas with a sound transducer, you
can heat it up just fine, with no need for implausibly
high velocities or other heroic measures. The heating
_per cycle_ will be small, but if you do it 10,000 times
per second for a long time, it adds up to something quite
significant.

Fair enough, but is it really all that different in spirit from a human arm? Say I use a diaphragm of a loudspeaker (not exactly what you had in mind, but perhaps you'll allow me to stretch to make the point) with a peak-to-peak motion of 1/2 mm. At 10 kHz, that's going to mean average speeds on the order of 10 m/s (and peak speeds higher yet), comparable to what I'm going to do with the adiabatic apparatus I'd guess. Granted you've got to run longer because your compression ratio is much smaller ... but I was just thinking about the speeds. -Carl
--
Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-1363
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/