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Re: [Phys-l] Isothermal and Internal Energy

On 08/23/2010 12:49 PM, James McLean wrote:

It is easy to find web pages that forget about phase transitions and
state that dT=0 => dU=0.

Ick.

My question:
>>> Aside from phase transitions, are there other isothermal processes
that result in an internal energy change? <<<

a) Chemical reactions routinely violate that both ways:
dT=0 dU<>0
dT<>0 dU=0

b) Find a slightly "leaky" capacitor (or just attach a low-conductance
shunt). Charge it and leave it a thermally isolated container.

c) A high-Q mechanical oscillator in a box is another example.

*) etc. etc. etc.... Construct your own.

=====================

Bottom line: temperature is not the same as energy. Really,
really not.