Newton's laws are only applicable to non-accelerating frameworks. For a car moving round a circular track, frictional forces at the ground acting on the wheels provide the centripetal force. The acceleration it produces is therefore similarly directed toward the center. It is called the centripetal force because it acts toward the center of the circle.
Here the force is due to the tension in the string and one can feel this force on the hand as the stone is whirled round. If the string were cut at any instant, the stone would fly off along a tangent to the circle (as seen in the sparks flying off a rotating Catherine-wheel).Ī force must be acting on the rotating stone to produce its acceleration. When a stone is tied to the end of a string and whirled round in a circle at constant speed, the velocity's magnitude is unchanged but the direction alters continuously.
