You and Al are both floating freely in your spaceships.Suppose Al is moving away from you at 85 km/hr.You throw a ball in his direction at a speed of 75 km/hr.According to Al,which of the following is going on?
A)He agrees that he is moving at 85 km/hr and the ball is moving at 75 km/hr while you are standing still.
B)He sees you moving away from him at 85 km/hr and the ball moving toward him at 75 km/hr.
C)He sees you moving away from him at 85 km/hr and the ball moving toward him at 10 km/hr.
D)He sees you moving away from him at 85 km/hr and the ball moving away from him at 10 km/hr.
E)He sees you moving toward him at 85 km/hr and the ball moving toward him at 75 km/hr.

Question

Quizplus · Accepted Answer

This question can be solved by using the concept of relative velocities. From your point of view, you throw the ball with a speed of 75 km/hr in the direction of Al, who is moving away from you at 85 km/hr. Therefore, the relative velocity of the ball with respect to Al will be:

Relative velocity = Velocity of ball thrown by you - Velocity of Al

Relative velocity = 75 km/hr - 85 km/hr (since Al is moving away from you, his velocity will be negative)

Relative velocity = -10 km/hr

Therefore, Al will see the ball moving in his direction, but with a speed of only 10 km/hr (since the ball's speed is reduced by Al's velocity of 85 km/hr). Hence, the correct answer is D, i.e., he sees you moving away from him at 85 km/hr and the ball moving away from him at 10 km/hr.

You and Al Are Both Floating Freely in Your Spaceships