Female Speaker: It is the sudden changes of speed and direction that produce the thrill of the Roller Coaster ride. The changing forces that act on the car push and pull the passengers out of their natural straight line motion. The car is pulled rapidly downward by the force of gravity, the force that pulls all actions toward the earth. The car plunges until it reaches the bottom of the diff where the rails raise again. These abrupt changes make the passengers lurch as they speed along the tracks.