Chapter 10, Problem 45A

To determine

The reason that the centripetal force does not do work on a circularly moving object.

Answer to Problem 45A

It is because the centripetal force acts in the perpendicular direction to the motion of the object.

Explanation of Solution

Introduction:

Work done by a force $F$ is given by,

  $W=Fd\cos \theta$

Where,

  $d=$ distance moved by the object

  $\theta =$ angle between the distance covered and the force applied

Now the centripetal force acts along the radius of the circle, while the tangential velocity of the object moving in a circle is always along the tangent at the considered point.

Hence, the centripetal force will always be perpendicular to the direction in which the object is being displaced due to which the work done will always be zero.

Conclusion:

Therefore, the centripetal force does not do any work on the object moving in a circle.