Introduction

Up to now, we have only analyzed the dynamics of point masses (i.e., objects whose spatial extent is either negligible or plays no role in their motion). Let us now broaden our approach in order to take extended objects into account. Now, the only type of motion which a point mass object can exhibit is translational motion: i.e., motion by which the object moves from one point in space to another. However, an extended object can exhibit another, quite distinct, type of motion by which it remains located (more or less) at the same spatial position, but constantly changes its orientation with respect to other fixed points in space. This new type of motion is called rotation. Let us investigate rotational motion.