# Physics No one has responded could someone help

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A 61 kg soccer player jumps vertically upwards and heads the 0.45 kg ball as it is descending vertically with a speed of 29 m/s. 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

If the ball is in contact with the player's head for 20 ms, what is the average acceleration of the ball? (Note that the force of gravity may be ignored during the brief collision time.)
m/s2

• Physics No one has responded could someone help - ,

• Physics No one has responded could someone help - ,

In an elastic collision, kinetic energy is conserved. The kinetic energy of the player and the ball just before collision is equal to that after collision. Assume that just after heading the ball, the velocity of the player is zero.

You can also use the conservation of vertical momentum.