Question

A ball is kicked off the back of a pickup truck traveling at 50 km/hr .A pedestrian on the ground sees the ball hit the pavement and then bounce straight up. What was the velocity of the ball relative to the truck?

Answer 1

The relative velocity of the ball to the truck = 50 Km/h.

Explanation:

We need to assume that the relative ball velocity is in the same direction as the truck velocity, meaning horizontal. We do not have accurate information in this regard from the question. So the ball would need essentially zero horizontal velocity relative to the ground in order to bounce straight up. This means that the relative velocity of the ball to the truck was 50 Km/h. We note that this situation assumes that the ball does not spin as spinning would cause the ball to deflect sideways after bouncing off the pavement in that case.