A roller coaster car has a speed of v0 = 5.9 m/s as it arrives at the crest of a h = 39.5 m drop. What is the car's speed at the bottom of the drop, vf in m/s?
a. 28.8 m/s
b. 20.2 m/s
c. 0 m/s
d. 34.3 m/s