please help me with these questions:

A ball has a mass of 6.0 kg and a velocity of 5.0 m/s [E30N]. After rolling across the floor (of negligible friction) it collides with another stationary ball of equal mass. After a elastic collision, the first ball has a velocity of 2.8 m/s [W60S]. What is the velocity of the other ball after the collision?A tennis ball with mass 59 g is travelling at 42 mfs [W] when it is intercepted by a tennis racquet that applies an average force of 200 N during a short period of time, after which the ball travels at 64 me [E]. What is the time of contact between the ball and the racquet? A massspring system undergoes SHM. The elastic potential energy at maximum stretch is 9.50 J, the mass is 0.30 kg, and the spring constant is 250 me. Calculate the period and amplitude of oscillation