A steel ball of mass 10kg moves due east at 5.0m/s. It collides with a rubber ball of mass 5.0 kg moving at 10m/s due north. After the collision the steel ball moves at an angle of 60 degrees East of North with a speed of 4.0 m/s. If the collision were perfectly elastic what would be the speeds of the two balls after the collision? Where do I start. I know total momentum before = total momentum after. But there seems to be 2 variables. vafter for steel ball and v after for rubber ball. Can an elastic collision have the 2 objects even stick together? If so then i got 1.92m/s.