Tempertaure of a moving object vs. stationary one

Main Question or Discussion Point

Hello.
If temperature is defined by the average kinetic energy of molecules, does this mean that moving an object in space increase it's temperature? (Or, say, looking at it from another inertial frame of reference?).

Thanks a lot!
Mike

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temperature is the system's *internal* energy, which includes molecular translational, rotational and vibrational motion. it does NOT include the system's *net* kinetic energy, which would be say... a piece of rock moving really fast, as opposed to a piece of rock that's still - the internal motion of the silicon/oxygen/iron/magnesium/carbon that make up the rock, stays the same.

if it were otherwise, things could have arbitrary temperatures, since you can always find a frame that's moving arbitrarily fast (within the speed of light) relative to another.

sophiecentaur
Gold Member
If you put 1J of energy into a piece of rock, you can either move it a bit or warm it up a bit. Same amount of energy but it's much more accessible (to reclaim) when it's non-random motion then when it's 'thermal'. The distinction is so relevant that we give the two forms of energy two different names.

I'm a bit of a Novice but the part of Kinetic Energy V^2(KE=1/2MV^2) I have noticed that it is apart of many different equations which means it can be manipulated a lot by different forces which affect the velocity of the object or particle so I'm sure you can increase the velocity without increasing the temperature.

sophiecentaur
Gold Member
I'm a bit of a Novice but the part of Kinetic Energy V^2(KE=1/2MV^2) I have noticed that it is apart of many different equations which means it can be manipulated a lot by different forces which affect the velocity of the object or particle so I'm sure you can increase the velocity without increasing the temperature.
Well, there's an awful lot of really cold stuff hurtling around in space at amazingly high speeds. Massive available energy in the form of KE if it hit us but not enough thermal energy to nudge a thermometer (travelling alongside it).