View more lessons like this at http://www.MathTutorDVD.com In this lesson, we will discuss the kinetic molecular theory of gases in chemistry and physics. In this theory, we define the velocity of of the gas molecules as being related to the kinetic energy of a gas particle. The average kinetic energy of all of the molecules in the gas is defined to be the temperature of the gas. In this way, we relate the physical quantity of energy to the thermodynamic quantities of temperature and pressure.