A 60 kg skier leaves the end of a ski-jump ramp with a velocity of 24 m/s directed 25 degrees above the horizontal. Suppose that as a result of air drag the skier returns to the ground with a speed of 22 m/s, landing 14 m vertically below the end of the ramp. From the launch to the return to the ground, by how much is the mechanical energy of the skier-Earth system reduced because of air drag?