Our first foray into linear motion was with kinematics, and we start our discussion of rotation with the same topic.
Rigid Body Rotation
Whenever we talk about “rotation,” there is something that is generally implied – we are not talking about a point mass or a collection of independently-moving point masses. Instead, we are generally referring to the rotation of a rigid object. A rigid object is nothing more than a collection of point objects that are confined to stay at specific positions relative to each other. When we talk about rotation, all these point objects follow different paths and travel different distances, but they all have something in common.