Physics
posted by Alex .
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 headon 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.
Sorry for the triplepost. Please ignore whichever immature person answers this using my name.

momentum can be found by multiplying mass and velocity together.
a) (4kg)(3m/s)(4kg)(2m/s) 
Use the definition of change in momentum, a vector operation.
changeinmomentum= Finalmomentum initial momentum
= massfinal(velocityfinal)massinitial(velocityinitial)
= mass (VfVi)
Now remember, you have direction associated with Vf and Vi.