A 2.0 kg block slides along a frictionless tabletop at 6.0 m/s toward a second block (at rest) of mass 4.5 kg. A coil spring, which obeys Hooke's law and has spring constant k = 850 N/m, is attached to the second block in such a way that it will be compressed when struck by the moving block. (a) What will be the maximum compression of the spring? (b) What will be the final velocities of the blocks after the collision? (Assume the initial direction of the 2.7 kg block is positive.) (c) Is the collision elastic? (Compare energy values to the nearest joule.) I don't know how I should treat the spring attached to the mass...and does the 4.5kg move when the first block hits it?