Amy (mass 60kg) and initial velocity +7.5m/s, is skating on ice toward Bob (mass 90kg) and initial velocity +4.0m/s. They collide at some point. Assume the collision is inelastic, what is their final speed? if their collision is elastic, what is their final speed? Assume Bob's final velocity is +6.0m/s which is partly inelastic. Determine amys final speed?