Calculate the change in momentum in each of the following situations and state the direction of the change in momentum.

a) A 4kg bowling ball strikes a stationary pin head-on at a speed of 3m/s. It continues to move in its original direction, but its speed is reduced to 2m/s.

b) A 200g rubber ball falling vertically strikes ground at a speed of 10m/s and bounces vertically upwards, leaving ground at speed of 6m/s.

c) A 4kg bowling ball moving at 2.5m/s strikes a pin in a glancing fashion. It is deflected through an angle of 10degrees. It's speed is reduced to 2m/s.

Can someone please explain how change in momentum can be calculated first of all and then go over the those questions and please explain what you did.