Cassy shoots a large marble (marble a, mass: 0.06 kg) at a smaller marble (marble b, mass: 0.03 kg) that is sitting still. marble a was initially moving at a velocity of 0.7 m/s, but after the collision it has a velocity of –0.2 m/s. what is the resulting velocity of marble b after the collision? be sure to show your work for solving this problem along with the final answer.