Motion In A Circle

Abstract

According to Newton’s First Law, a body in motion will continue to move along a straight line with uniform velocity unless acted upon by an external force. Hence any body which moves in a circular path must be acted upon by a radially inward force to overcome the tendency of the body to fly off along a tangent, Figure 3.1. In the case of a stone rotating on the end of a string, this force is provided by the tension in the string; in the case of the moon rotating round the Earth, it is provided by the gravitational attraction exerted on the Moon by the Earth. This radially inward force is termed the centripetal force and the acceleration produced by this force is termed the centripetal acceleration.