A ball with a mass of #7 kg# moving at #4 m/s# hits a still ball with a mass of #9 kg#. If the first ball stops moving, how fast is the second ball moving? Physics Momentum and Collisions Conservation of Momentum 1 Answer A08 Jan 16, 2016 #=3.1 dot 1 m/s# in the direction of motion of the first ball. Explanation: See A ball with a mass of #8 kg# moving at #7 m/s# hits a still ball with a mass of #12 kg#. If the... Answer link Related questions Why does Newton's cradle stop? How does the conservation of momentum apply in rotational motion? How does the conservation of angular momentum effect the stability of a bike? What is the law of conservation of momentum? What is conservation of angular momentum? What is an inelastic collision? What are some examples of an elastic collision? What is an elastic collision? What is the conservation of momentum? A fly splats on your windshield. What is the collision type? See all questions in Conservation of Momentum Impact of this question 1178 views around the world You can reuse this answer Creative Commons License