Rvfm kinetic theory model rvfm edu038 this model provides in analogue form a visual representation of molecular movement in gases p p a piston in a wide perspex tube is vibrated by a low voltage electric motor housed in a box supporting the tube tiny metal spheres simulating gas molecules are propelled upwards in a tube by the piston s vibrations the movements of the spheres are seen to be random both in direction and extent p p the motor is provided with a speed control higher