A truck starts from origin, accelerating with `a m s^-2` in positive x - axis direction. After `2 s`, a man standing at the starting point of the truck projected a ball at an angle `30^@` with velocity `v m s^-1`. Find the relation between `a and v` such that the ball hits the truck. (Assume that truck is moving on horizontal plane and the man projected the ball from the same horizontal level of truck).