A 1-kg ball initially moving with a speed of 3m/s strikes a stationary 2kg ball head-on. After the collision both balls stick together. What are the final velocities of the two balls?

Answer 1

momentum must be conserved:

1*3 + 2*0 = (1+2)v

Although, I fail to see how they could properly roll, if sticking together after such a collision.

Answer 2

4.5