Uniform Circular Motion 

a = Centripetal Acceleration 

v = Velocity 

r = Radius  

F = Force 

w = Angular Velocity

 Circular motion is caused when an object experiences just the right amount of net force directed toward the center of the circle or curve. The acceleration of an object in uniform circular motion is always toward the center of the circle.  The acceleration and the force causing it are called centripetal which means center-seeking. Centripetal force can be provided to a planet by gravity, to a car by friction between wheels and the road, or to a ball the the tension on a string. Since the direction of the velocity of the object is continuously changing toward the center of the circle, the object is said to experience centripetal acceleration, even though its speed is constant. 

Definition provided by Physics 24/7

More of my videos

A great website for simple machines in automobiles (Thanks Alyssa)

Khan's Videos on circular motion