physics questions?

[LUckyyou :)]

To unload a truck, boxes are allowed to slide down a ramp where they are picked up and carried away. The 3.5 m long ramp has a coefficient of kinetic friction of 0.30 and makes a 30º angle with the horizontal.


a.If a 24 kg box slides down the ramp (starting from rest), how much work is done by friction?


b.If a second box, more massive than the first, slides down the ramp, is the work done by friction on the second box more than, equal to, or less than your answer to part (b)?



A 0.6 kg tennis racquet initially moving to the right at 10 m/s collides with a 0.1 kg tennis ball. Before the collision, the ball is moving to the left with a speed of 20 m/s. After the collision the ball is moving to the right with a speed of 25 m/s. The collision lasts for 10-3 s.
a.Find the impulse delivered to the ball by the bat.


b.With what average force did the racquet hit the ball?


c.What is the final velocity of the racquet after the collision?