A 56.0-kg projectile is fired at an angle of 30.0° above the horizontal with an initial speed of 1.24 102 m/s from the top of a cliff 120 m above level ground, where the ground is taken to be y = 0.
(a) What is the initial total mechanical energy of the projectile?
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(b) Suppose the projectile is traveling 87.9 m/s at its maximum height of y = 280 m. How much work has been done on the projectile by air friction?
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(c) What is the speed of the projectile immediately before it hits the ground if air friction does one and a half times as much work on the projectile when it is going down as it did when it was going up?