Ok. So I have spent about 40 mins on this question, and can't seem to get it. I know how to conserve momentum when an object hits another at rest, using the cosine and sine laws. but this question involves two objects both moving at different angles. We'll, here it is, if anyone can help: Two rolling golf balls of the same mass collide. The velocity of one ball is initially 2.70m/s[E] . After the collision, the velocities of the balls are 2.49m/s [62.8 degrees N of W] and 2.37m/s[69.2 degrees S of E]. What is the magnitude and direction of the unkown initial velocity? The answer is 3m/s[W}...Any help would be greatly appreciated...Thanks.