Earth revolves round the sun (say in a circular path under the action of the force exerted by the sun on the earth. Is the sun doing any work ? Explain .

Explanation

Centripetal force (Which is provided by gravitational pull of the sun in this case) that acts on a body in a circular motion is perpendicular to the displacement of the body at every point of its motion, and hence does not do any work. Component of this force in the direction of the displacement `=F cos 90^@=0` (F =applied force). So, gravitational pull of the sun does not do any work for the revolution of the earth as the force acts perpendicular to earth.s direction of displacement .