A tennis player swings her 1000 gram racket with a speed of 11.0 m/s. She hits a 60 gram tennis ball that was approaching her at a speed of 20.0 m/s. The ball rebounds at 40.0 m/s,
a) Find how fast is her racket moving immediately after the impact?
b) If the tennis ball and racket are in contact for 7.00 milliseconds, estimate the average force that racket exerts on the ball?