A 50.0-kg projectile is fired at angle of 30.0 degrees above the horizontal with an initial speed of 120 m/s from the top of a cliff 142 m above level ground, where the ground is taken to be y = 0.
(a) What is the initial total mechanical energy of the projectile?
(b) Suppose the projectile is traveling 85.0 m/s at its maximum height of y = 427m. How much work has been done on the projectile by air friction?