Question

Starting from rest, a child throws a ball of mass m with an initial speed v , at an angle B with the horizontal direction. The child then chases after the ball, accelerating at a constant acceleration a . If the child wants to catch the ball at the same height as it was thrown, what must be the child's acceleration a ? Express your answer in terms of some or all of the variables v , m , B and g for the gravitational constant. Express the trigonometric functions in terms of the basic sin(B), cos(B) or tan(B).