A projectile is launched horizontally at a speed of 40 meters per second from a platform located a vertical distance h above the ground. The projectile strikes the ground after time at horizontal distance from the base of the platform. [Neglect friction.] Calculate the vertical distance, h, if the projectile's total time of flight is 4.5 seconds. You must show work to earn full credit with the minimum 3 steps:
1. Equation used
2. Substitution with correct units
3. Final answer with correct units