1. Uniform Circular Motion (UCM) – Occurs when an object moves in a circle at a
constant speed.
Is the object accelerating?
Yes, even though the object is not changing speed it is changing velocity because it changes direction.
Tangential Velocity

2. What direction are the force and the acceleration?
(Center Seeking)
Centripetal Force – The inward directed net force acting on an object undergoing UCM
Centripetal Acceleration – The inward directed acceleration of an object undergoing UCM

3. You may have heard of...
(Center Fleeing)
Centrifugal Force –
A fictitious outward directed force only “felt” by an object moving in Uniform Circular Motion.
Consider the eraser on the string:
Notice, no outward directed force. Only the inward directed tension force keeping the mass moving in UCM.