The car is changing direction because of a force (supplied by friction between road and tires) directed toward the center of the curve. That is the centripetal force, which is always directed toward the center of the curve. When you swing a weight around your head at the end of a string, your hand supplies the centripetal force to keep the weight moving in a circle. Back inside the car, you feel a force pushing you AWAY from the center of the curve. That force is called centrifugal force, which is always equal in magnitude but opposite in direction from centripetal force. Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor.