試題詳解

39. A 5.0-kg ball is dropped from a cliff. Given the resistive force is R = (0.49 kg/m)v², where v is the speed of the ball, and the gravitational acceleration is g = 9.8 m/s², what is the terminal speed the ball?
(A) 4.9 m/s
(B) 10 m/s
(C)40 m/s
(D) 2.0 m/s
(E) 20 m/s