Two balls Y and Z collide elastically in space. If Z is initially at rest how would you choose it's mass in relation to Y so that it would recoil with the greatest (1) KE (2) Momentum Kinetic Energy: KE = (1/2)mv^2 Momentum: P = mv Would you have to have a smaller mass for Z so that it would recoil with greater KE than Y? And for momentum would you have to have a larger mass for Z so it would recoil with greatre momentum? How do you explain them in terms of the equations? I think I understand the momentum....if you plug in larger mass than you have a larger P...but KE I'm not sure? Wouldn't you also have a larger KE if you plugged in larger mass? If Z was really large it wouldn't move it all so I would think it would have to be small would it not?