The Angular Momentum Theorem

The previous chapters have dealt with problems of translational motion. We now begin an investigation of motions where rotation is an important ingredient. We start by associating with one particle the so-called angular momentum, defined with respect to some reference point often taken to be at rest in an inertial frame. These considerations will then be extended to a system of particles. Forming the angular momentum for a system of particles with respect to the center of mass (CM), we shall see that the equation of motion for this angular momentum has a simple form, even if CM is accelerating.