Suppose a soccer player kicks the ball from a distance 29 m toward the goal. find the initial speed of the ball if it just passes over the goal, 2.4 m above the ground, given the initial direction to be 39° above the horizontal.

The ball's vertical velocity at the time it just passes over the goal is 0 m/s. Its initial vertical velocity is unknown and we denote it by , where here is the ball's initial speed. Vertically, the only force acting on the ball is gravity, which attributes a downward acceleration of 9.8 m/s^2. We expect the maximum height achieved by the ball to be 2.4 m, so we can find the initial speed by solving