\u3ci\u3ePhysics\u3c/i\u3e, Chapter 6: Circular Motion and Gravitation

Our earlier discussion of the kinematics of a particle was developed principally from the point of view of being able to describe that motion easily within a rectangular coordinate system. Thus the most complex case with which we dealt was that of a projectile motion, in which the acceleration was constant and was directed along one of the coordinate axes. A more convenient framework within which to discuss rotational and circular motions is provided by a set of polar coordinates. In the present discussion we will restrict ourselves to motion in which the polar coordinate r is constant, or fixed; that is, the particle is constrained to move in a circular path