Law of Conservation of Momentum

I've realized that when looking at a collision, the momentum remains the same in it; however, what we see is the change in velocity. An example would be a 2kg Velcro ball traveling 30m/s that made contact with a 10kg Velcro block initially at rest. When the collision occurred, they stuck together and traveled 5m/s. If you were to look at the momentum before and after the collision, the momentum is the same. Therefore, no matter the type of collision, although the velocity in a collision may vary, the momentum remains the same.