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Chemomechanics t1_jbzk7qu wrote

No; the kinetic energy corresponding to the temperature is measured relative to the center of mass. A cold body moving fast doesn't appear hot, as the relative undirected motion of the particles is unchanged. (However, two cold bodies colliding inelastically would get hotter, of course.)

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mesouschrist t1_jc1zp7k wrote

Your answer seems to imply that if the system was spinning, you would call it higher temperature, because you can't "remove" the motion by going to the center of mass frame. I agree that it's useful to gasses to go to the center of mass frame to restore the distribution of velocities to a Maxwell-Boltzmann distribution so it looks more like a system with a well-defined temperature. However, I don't think there's anything in any reasonable definition of temperature that says "it's measured relative to the center of mass"

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Chemomechanics t1_jc2nqn9 wrote

> Your answer seems to imply that if the system was spinning, you would call it higher temperature

That would be a misreading, because the context of the answer is a question about translational motion. More generally, the bulk motion is typically subtracted before we do thermodynamics. If you don’t see that stated in definitions of temperature, it’s because it’s already been implicitly assumed.

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