A Tennis Ball Is Thrown Vertically with an Initial Speed

Multiple Choice

A tennis ball is thrown vertically with an initial speed of 20.0 m/s at time t = 0 s. Approximately, what is the initial speed of the ball relative to an observer in a car that moves horizontally past the launch location with a constant speed of 30 m/s?

A) 10 m/s
B) 20 m/s
C) 30 m/s
D) 36 m/s
E) 50 m/s