posted by anonymous on .
19. (2 points) Ball 2, with a mass of 30kg, is moving to the left at 10m/s. With what velocity should Ball 1, with a mass of 10kg, move to the right and collide with Ball 2, so that Ball 1 rebounds with a velocity of 30m/s, and Ball 2 with a velocity of 10 m/s, after the collision? Assume the collision to be perfectly elastic.