1. The problem statement, all variables and given/known data A block of mass m1 slides along a frictionless table to the right with a speed of v1. A second mass M2 slides in the same direction with a speed of v2 such that it will collide with m1 which is in front of m2. Say that a spring of stiffness k is attached to one of the masses such that it compresses when the two masses finally collide. Find the maximum compression of the spring. 2. Relevant equations It sounds like momentum to me so I guess F=dp/dt will be relevant here. 3. The attempt at a solution Now I think max compression occurs when velocity of mass 1 relative to mass 2 is zero. But that's the only thing I could really figure out. I don't know what to proceed next. Can anyone help me?