A question on gravity?

If the earth were stationary reletive to the sun, it WOULD fall into the sun.

With equal centripetal (from gravity) and centrifugal (form it's orbit) forces, an object maintains it's distance.

The orbit of the Earth is a delicate balance between gravity, which pulls things toward the centre of the orbit, and centrifugal force, which pushes things outward from the centre.

The kinetic energy of Earth, combined with the centripetal (centre-tending) force of gravity, give rise to a reactionary centrifugal force.

If Earth's orbital velocity slowed, then the centrifugal force would lessen, and its orbit would become smaller. If it slowed enough, Earth would fall into the sun.

If Earth's orbital velocity increased, the centrifugal force would increase and the orbit would become larger. Increase the velocity enough and Earth breaks free of the sun's gravity altogether and is flung out into space.

There are two forces in constant battle with each other. 1. The earth is revolving around the sun therefor forcing itself away from the sun. 2. The sun's gravitational pull is strong enough to keep the earth from leaving the sun but is not strong enough to pull it into the sun. Just like spinning a tennis ball on string.

The answer to your question in in the big bang theory.

We know the formula of centripetal force

F=massxsquare of velocity/radius

This formula shows that centripetal force acts on a body having some orbital radius and some velocity.Why did i stated big bang theory?

Actually the big bang caused the pieces of big flame ball to disperse in space.Initial force of big bang threw our earth at sufficient distance and gave it a suitable radius and velocity so that centripetal force equivalent to centrifugal force acted on it and it is not pulled in the centre of the sun.

consider an example.....

you had rope in which a ball is attached at its end.....

the ball is kept 10 feet away from you in ground and the rope is in in your hand now a machine came and it gave a very high velocity to the ball on the side that is he gave a large velocity perpendicular to the rope in left or right direction.

now if you left the rope then the ball will go straight in direction in which velocity was given but if you kept on holding the rope the ball will revolve around you and you have to rotate to keep you eyes on the ball..

same case is in solar system..

the force you provided to the rope is equivalent to the gravitation force that sun apply on earth the only thing changed it there is no rope and the force line in invisible......

now in earth the ball will stop after sometime due to atmospheric friction. but in space there is no atmosphere so earth continues to revolve and revolve....

hope this is what you have asked for...