Answer:
(3) the same before and after the collision
Step-by-step explanation:
The sum of products of mass and velocity before the collision is ...
(2 kg)(0.250 m/s) + (2 kg)(0 m/s) = 0.50 kg·m/s
The sum of products of mass and velocity after the collision is ...
(2 kg +2 kg)(0.125 m/s) = 0.50 kg·m/s
The total momentum is unchanged.