The kinetic molecular theory of Maxwell and Boltzmann proposes that the macroscopic properties of an ideal gas derive from the fact that it is composed of a large number of colliding point particles that are in rapid motion.
The particles do not interact with one another except in elastic collisions. The piston receives from each such collision a certain amount of momentum. The macroscopic effect of these collisions is pressure.
Click and drag the piston horizontally to modify the volume