1. Circular Motion Centripetal Acceleration

2. Revisiting Acceleration What is acceleration? Acceleration is how fast an object’s velocity changes. But what is velocity? It is the vector representing how fast an object is moving, AND the direction it is moving. So what is acceleration? Acceleration is how fast an object’s speed and/or direction of motion is changing.

3. A “new” kind of acceleration ViVi VfVf We have looked to see how to calculate the acceleration of an object when its speed changes. a ViVi VfVf a If an object travels in a circle there must be an acceleration because the direction of the object’s velocity is changing. Even if the speed is constant, there must be an acceleration. V V V V V V V V Since the velocity is tangential to the circular path of motion, the acceleration must be pointing to the center of the circular path at all times. We call this centripetal acceleration. (Centripetal means center-seeking) a a a a a a a a V V V V V V V V acac a = V f - V i t

4. Calculating a c Centripetal Acceleration is calculated using the equation a c = (Speed) 2 /radius a c = v 2 /r The speed of an object is found from its definition Speed = distance/time » The distance traveled is the circumference of a circle (2  r) multiplied by the number of revolutions. Speed = (#revolutions)(2  r)/time