Chapter 6.4, Problem 6.4TYU

The air surrounding an airplane in flight exerts a drag force that acts opposite to the airplane’s motion. When the Airbus A380 in Example 6.9 is flying in a straight line at a constant altitude at a constant 250 m/s, what is the rate at which the drag force does work on it? (i) 432,000 hp; (ii) 108,000 hp; (iii) 0; (iv) −108,000 hp; (v) −432,000 hp.