Centrifugal versus centripital, as explained on the answer bag. Centrifugal force is a perceived force, not an actual force. It can only be viewed from the vantage point of the spinning object. For example, when turning in a car, the object in the seat next to us flies outward. We call that centrifugal force. Remember the law of intertia: all objects stay at rest or continue in a straight line unless acted on by an outside force. The object that flies outward is trying to continue in a straight line (the direction the car was headed before you started turning). There is just not enough friction on the seat next to you to keep the object constrained to the turn until it hits the door. If you add the vectors of movement on the turning car, it is found that the car is accelerating towards the center of the turn, not away from the center. This inward acceleration is called centripital force. That feeling of being "pushed out" when turning in a car is nothing more than resistance to the centripital force constraining the car.
