punchthis22 Ina shoots a large marble (Marble A, mass: 0.08 kg) at a smaller marble (Marble B, mass: 0.05 kg) that is sitting still. Marble A was initially moving at a velocity of 0.5 m/s, but after the collision it has a velocity of –0.1 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. There seems to be something wrong here. Using conservation of linear momentum with the numbers given, I can work out a resulting velocity for v. BUT ... To check it, I’ve tried to apply conservation of kinetic energy, or at least COMPARE the kinetic energies before and after collision. Before After According to this, there’s MORE kinetic energy AFTER the collision than before. Which should be nonsense ?

Before B A Momentum Total momentum before collision After B A Momentum Total momentum after collision

Total momentum before collision Total momentum after collision B A B A The smaller mass gets a big kick from the larger mass. (Hence maybe the expression “pick on someone your own size”.)

Total kinetic energy before collision Total kinetic energy after collision According to this, there’s MORE kinetic energy AFTER the collision than before. Which should be nonsense ?