Question

Thermodynamics and Statistical Mechanics problem:

In regard to the Maxwell speed distribution, you might wonder why all the molecules in a gas in thermal equilibrium don’t have exactly the same speed. After all, when two molecules collide, doesn’t the faster one always lose energy and the slower one always gain energy? And if so, wouldn’t repeated collisions eventually bring all the molecules to some common speed? Describe an example of an elastic billiard ball collision in which this is not the case: the faster ball gains energy and the slower ball loses energy. Include numbers and be sure that your collision conserves both energy and momentum.

Answer 1

So, the faster one will tend to have lower the mass as it cannot lower it's mass it decreases it's kinetic energy (which is proportional to mass) and transfer it to slower one to get in statistical and thermo dynamical equilibrium.