Chapter 9

Centripetal Forces: Rotational Motion

Circular and rotational motions are widespread both in nature and in man-made machines, from merry-go-rounds to the orbits and spins of planets. To analyze and model such types of motion, we need some special tools: the linear kinematics and dynamics presented in Chapter 5 need to be extended to rotational motion. In a nutshell, this is what the present chapter will begin to look into.

Topics covered in this chapter include the following:

• Kinematics of uniform circular motion: The kinematics of rotational motion can be developed in analogy with linear kinematics.
• Centripetal acceleration and centripetal force: An object in uniform circular motion still experiences acceleration and therefore a force directed toward the center of rotation.
• Non-uniform circular motion: This happens if there is a tangential component of force in addition to a centripetal component.

The material covered in this chapter will also be relevant for handling rigid body motion in Chapter 13.