Question

State the source of centripetal force that a planet requires to revolve around the sun. On what factors does that force depend? Suppose this force suddenly becomes zero, then in which direction will the planet begin to move if no other celestial body affects it?

Answer 1

The centripetal force required by a planet to remain in the orbit around the sun is provided by the gravitational force of attraction between the planet and the sun.

The centripetal force (F) depends on the radius (r) of the planets orbit, mass (m) of the planet and orbital speed (v) of the planet.

F = mv²/r

If the force suddenly becomes zero the planet will fly off in a direction tangential to the original direction of motion which was a circle.