Aball is released at the point x=2m on an inclined plane with a nonzero initial velocity. after being released, the ball moves with constant acceleration. the acceleration and initial velocity of the ball are described by one of the following four cases: case 1, a> 0,v0> 0; case 2, a> 0,v0< 0; case 3, a< 0,v0> 0; case 4, a< 0,v0< 0.