A ball of unknown mass is tossed straight up with initial speed . At the moment it is released, the ball is a height ℎ above a spring-mounted platform, as shown in the figure. The ball rises, peaks, and falls back toward the platform, ultimately compressing the spring a maximum distance from its relaxed position. Assume that the spring is perfectly ideal, with spring constant , and that the mass of the spring and platform is negligible. What is the mass of the ball, , assuming that there is no friction or air resistance?

Using to represent the acceleration due to gravity, enter an expression for in terms of , ℎ , , , and .