question_answer 49)

  What is the source of centripetal force that a planet requires to revolve around the sun? On what factors does that force depend?

Answer:

  The motion of the planet around the earth is due to the centripetal force. This centripetal force is provided by the gravitational force between the planet and the sun. This force depends on the mass of the sun and mass of the planet, and on the distance between sun and planet.