Question

what causes earth to rotate and revolve

Answer 1

The Earth was likely formed from matter that was part of the nebula that condensed and formed the Sun.  As that matter condensed, conservation of angular momentum required the condensing cloud to rotate at a greater rate.  So, not only does the sun spin, but any matter from the nebula that did not get pulled into the sun also revolves around the central point.

2) If the Earth did not revolve around the sun, it would be pulled, by gravity, into the sun.  Objects manage to keep their distance from the Sun by moving forward at about the same speed they are falling into the sun.  The summation vector of those two trajectories is an ellipse (orbit). 


Newton's cannon ball example is the simplest visualization of this.  Newton rationalized that if we fired a cannon ball, horizontally, it would travel in an arc dictated by the initial speed of the ball and gravity.  If we fired the ball faster, it went farther.  There must be a speed at which we could fire it and it would never hit the ground, because gravity would pull it into a closed circle above the surface.  However, if we fired it even faster, it would pull away from the Earth, and escape.