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

a_r = |v|²/r
a_t = slope of the graph of |v| versus t.