Question

Why measured temperature is the average K.E of air molecules?I mean how a 373K molecule and a 268K molecule have no transferring of heat and didn't reach equilibrium?I need details.

Answer 1

Heat is an energy transfer mechanism that manifests itself in the form of random kinetic energy for molecules. That is, heat transfers energy in a pretty random manner, and this energy is in the form of kinetic energy for individual particles in a substance.

So, when something is hot, it's molecules have a lot of kinetic energy. Thus, the scale that we use to measure this energy, temperature, is a measure of the average kinetic energy of the molecules in a substance.

I'm not sure that I understand the second part of your question. However, the two molecules would need to collide, and likely repeatedly, to reach thermal equilibrium through conduction.

Answer 2

The collision isn't the only way to transfer heat you know radiation can do.
Lets give an example of the second question which is vortex tube why air molecules are different in their temperatures that difference such that u can freeze your hand at one end on the vortex tube and burn it on the other end.