A 55-kg soccer player jumps vertically upwards and
heads the 0.45-kg ball as it is descending vertically
with a speed of 24 m/s. (Note that the force of
gravity may be ignored during the brief collision time.)
(a) If the player was moving upward with a speed of 4.0
m/s just before impact, what will be the speed of the ball
immediately after the collision if the ball rebounds vertically
upwards and the collision is elastic?
___ m/s
(b) If the ball is in contact with the player's head
for 18 ms, what is the average acceleration of the
ball?
___m/s2