Check Yourself (p. 68): After a skydiver jumps from a high-flying helicopter, her acceleration decreases. This happens because the ratio of net force to mass is decreasing as air resistance becomes stronger. As she jumps from the airplane, air resistance becomes stronger as her body falls more rapidly to the earth. This would make it seem like her acceleration is increasing, however, that is not the case. Newton’s Second Law of Motion says that when the net force is decreasing, and air resistance is increasing, this results in a decreased acceleration. Her acceleration is decreasing because, even though her body is falling more rapidly toward the Earth, air resistance is getting stronger and stronger. As soon as air resistance equals her weight, her acceleration will completely terminate (terminal speed).