In this chapter we take a different approach. We focus on the details of what happens during interactions, not just at net changes that occur as a result of interactions. We explicitly look at the time-dependence of the change of various parameters. We have already spent considerable time in the last two chapters learning how to work with forces to determine work and impulse and both translational and rotational motion. Here, we augment this knowledge to develop an approach to predict the detailed time dependence of motion from a knowledge of the net force and vice versa.