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.