Maxwell’s kinetic theory of gases is the long-established point of entry into the difficult but rewarding theory of statistical mechanics. This Molecular Motion Model provides a concrete, qualitative introduction.
Fifty-one chromed steel balls represent the molecules of a gas in a closed vessel. Heat is simulated by supplying vibrations from a wave driver. When this external energy is applied, the steel balls exert a pressure on the container, forcing the top of the container upward. The relationship between temperature, pressure and volume is clearly demonstrated. Students also gain insight into the effects of temperature and height on the density of an ideal gas in a gravitational field. It can be used on an overhead projector.