Question
Tue December 20, 2011 By:

work done by a centripetal force is zero.why?

Expert Reply
Wed December 21, 2011
Work = Force x displacement x cos 
As the centripetal force acts upon an object moving in a circle at constant speed, the force always acts inward as the velocity of the object is directed tangent to the circle. This would mean that the force is always directed perpendicular to the direction that the object is being displaced. The angle  in the above equation is 90o and the cosine of 90o is 0. Thus, the work done by the centripetal force in the case of uniform circular motion is zero.
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