If a body of mass 5og moves in a circular path of radius 10cm .find work done

0Nm, no work is done.

Explanation:

Work done is defined as the Force per distance meaning force times the distance moved in the direction of the force.

Now the body of mass 50g has a centripetal force acting on it directed towards the centre. Now in actuality the body stays along the circle it doesn't really move to the centre of the circle.

Hence the force doesn't move a distance, and so from the definition of work done;

F×d ; d =0

Hence work done = mv2/r × 0= 0Nm

c.the charges if the proton and electron and gravity

no. dot product   =0 when vecs at right angles