One object (m 1) has a mass of 2 kg and moves with a speed of 9 m/s to the right. Another object (m 2) has a mass of 3 kg and moves to the left with a speed on 3 m/s. The two objects collide. After the collision, the first object (m 1) moves to the right with a speed of 1.5 m/s. The second object (m 2) moves to the right at 2 m/s. ----- What is the change in the momentum of the first object (m 1) during the collision? (Remember that "change" is always "final − initial".)