A boy on a skateboard coasts along at 5 ms He has a ball tha

A boy on a skateboard coasts along at 5 m/s. He has a ball that he can throw at a speed of 10 m/s. What is the ball’s speed relative to the ground if he throws the ball a. forward? b. backward? c. to the side?

Solution

A, In forward direction

Speed = Vskate + Vball = 5 + 10 = +15 m/sec

As both speeds are in same direction so it will be added.

B. In Backward direction

Speed = Vskate - Vball = 5 - 10 = -5 m/sec

means ball will go by the speed of 5 m/sec in backward direction.

C. to the side

It is not clear on which side, So I will be unable to tell the direction

V = (Vskate^2 + Vball^2)^0.5

V = (25 + 100)^0.5

V = 125^0.5 = 11.18 m/sec