posted by anonim .
A football, if it was kicked when initially at rest, is inflated such that it will move in the direction of the kick with h=0.8 of the kicking foot's velocity
We now consider the same ball being kicked while it's moving towards the football player's foot. Before the kick the ball moves towards the soccer player with velocity v=10 m/s and the player kicks the ball in the opposite direction with foot velocity u=5 m/s.
What is the ball's speed after the kick in m/s?