Lectures on Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....

Summary - Circular Motion

If an object is to have circular motion, a force must be exerted on it toward the center of the circle. There is no outward force on the object; the illusion of an outward force comes from our experiences in which our point of view was rotating, so that we were viewing things in a noninertial frame.

An object undergoing uniform circular motion has an inward acceleration vector of magnitude

|a| = |v|2/r .

In nonuniform circular motion, the radial and tangential components of the acceleration vector are

ar = |v|2/r
at = slope of the graph of |v| versus t.

Last Update: 2009-06-21