Temperature and molecular Kinetic Energy

[ChrisXenon]

We are told that temperature measures the average kinetic energy of the molecules or atoms in a substance, but this cannot be true.
If I take a jar of water and put the jar in my car and drive it aorund, it won't get hotter, though it's kinetic energy must surely be higher.
Clearly, I've got something wrong here - is it due to the fact that there's a vague notion that this average kinetic energy is vibratory? Or something else?

Thanks

 

[russ_watters]

We are told that temperature measures the average kinetic energy of the molecules or atoms in a substance, but this cannot be true.
If I take a jar of water and put the jar in my car and drive it aorund, it won't get hotter, though it's kinetic energy must surely be higher.
Clearly, I've got something wrong here - is it due to the fact that there's a vague notion that this average kinetic energy is vibratory? Or something else?

You pretty much have it; the vibration (or bouncing around of gas molecules) is random and only relevant for the object's/gas's rest frame. The kinetic energy of bulk motion is separate.

 

[Lord Jestocost]

Heat is energy which is statistically distributed over all particles. Maybe, the following (“Thermodynamics and Statistical Mechanics” by Walter Greiner, Ludwig Neise, Horst Stöcker) might be of help:
Thermodynamics and Statistical Mechanics

 

[anorlunda]

If I take a jar of water and put the jar in my car and drive it aorund, it won't get hotter, though it's kinetic energy must surely be higher.

@russ_watters already mentioned the object's rest frame.

Have you considered that the car's velocity in the car's rest frame is zero. Or that the car's velocity relative to another car driving the same direction decreases as the car accelerates from a stop?

 

[ChrisXenon]

BAM! Outstanding. Thanks guys. I'm sorted.