What determine the revolution of the earth?

Answer 1

revolution of earth is because of the gravitational force exerted by sun. this force provides necessary centripetal force (cpf) for circular motion. now questin may come that why isn't earth pulled towards sun? this is because of two reasons 1. work done by cpf is zero 2. it is assumed that an equal and opposite force called as centrifugal force acts on earth which prevents it from getting pulled towards sun -------------------------------------- Quick correction: The reason the Earth isn't pulled towards the sun is not because there is another force. In fact, the centrifugal force is a fictitious force in a rotational (non-inertial and therefore not used) frame of reference and does not exist in an inertial fram of reference. For the real reason, consider this: -Objects in uniform motion want to stay in uniform motion. -Uniform motion is defined as a straight-line motion with a constant velocity. -Objects in uniform motion will change its motion (either speed or direction) only if there's an external force. -Therefore, the Earth will tend to move in a straight-line motion unless there's another force. In fact, if the sun suddenly disappears and when the gravitational force it exerts on Earth (the source of Earth's centripetal acceleration, ergo the identity of Earth's centripetal force) disappears after about 8 minutes, the Earth will shoot off in a tangent, moving in a straight line. -Therefore what the gravitational pull of the sun does is that it is just enough to bend the orbit of the Earth enough for it to be an ellipse while not allowing the Earth to gradually shoot off into space or crash into it. -If, as suggested above, another force completely balances out Earth's centripetal force (i.e. completely negates the gravitational force of the sun on Earth), the Earth's motion will no longer change and the Earth will shoot off into space with a straight-line motion.

Answer 2

The rotation of the Earth is determined by the conservation of angular momentum, which was set in motion during the formation of the solar system. The gravitational pull of the Sun and other celestial bodies helps maintain this rotation.