Homework: Watch Centripetal Acceleration Video and answer questions

The motion of an object in a circular path at constant speed is known as **uniform circular motion** (UCM). An object in UCM is constantly changing direction, and since velocity is a vector and has direction, you could say that an object undergoing UCM has a constantly changing velocity, even if

its speed remains constant. And if the velocity of an object is changing, it must be accelerating. Therefore, an object undergoing UCM is constantly accelerating. This type of acceleration is known as **centripetal acceleration**, and centripetal acceleration always points toward the center of the circle.

**Circular Speed**

So how do you find the speed of an object as it travels in a circular path?

The formula for speed that we learned in kinematics still applies.

v=d/t

We have to be careful in using this equation, however, to understand that an object traveling in a circular path is traveling along the circumference of a circle. Therefore, if an object were to make one complete revolution around the circle, the distance it travels is equal to the circleâ€™s circumference.

C=2*Pi*r