Believe it or not, you already understand all the underlying concepts of circular motion. Previous chapters defined quantities such as displacement, velocity, and acceleration. Now all you have to do is apply these same concepts to rotational motion. Let's start by looking at the motion of a CD-ROM when your computer is reading it. Figure 14.1 shows a top-down view of the spinning CD.
Figure 14.1. Point P on a CD-ROM.
The center point (C) represents the axis of rotation. A point on the CD (P) therefore rotates about the center, which means that it travels along a circular path with a fixed radius (r). After some time has passed ...