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Re: [Phys-l] T dS versus dQ

Not that this "he said - she said" matters, but I did not claim that the initial and final temperatures were the same. My claim was that the final temperatures would be the same if the process proposed would be done quickly or slowly.

Carl proposed a quick adiabatic compression in a cylinder, my claim was simply that if energy could not enter or leave the cylinder except through the motion of the piston then the rate of compression wouldn't matter and a reversible adiabatic compression (isentropic) should give the same result. An isothermal process would require energy transfer through the cylinder - which is not in the spirit of Carl's proposal. If one changes the original question then any claim can be justified.

Bob at PC

From: [] On Behalf Of John Mallinckrodt []
Sent: Wednesday, January 13, 2010 12:15 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] T dS versus dQ

Bob LaMontagne:

It seemed to me to be a not completely unreasonable conclusion from
the fact that you explicitly (and incorrectly) stated that the final
temperature would be the same as the initial temperature. You also
said (incorrectly) that a reversible adiabat would take you from the
initial state to the final state. I took those two explicit
statements to suggest that you might think that a reversible
adiabatic process is the same as an isothermal process.

John Mallinckrodt
Cal Poly Pomona

Forum for Physics Educators