In Figure block 2 (mass 1.0 kg) is at rest on a frictionless surface and touching the

Question:

In Figure block 2 (mass 1.0 kg) is at rest on a frictionless surface and touching the end of an un-stretched spring of spring constant 200 N/m. The other end of the spring is fixed to a wall. Block 1 (mass 2.0 kg), traveling at speed v1 = 4.0 m/s, collides with block 2, and the two blocks stick together. When the blocks momentarily stop, by what distance is the springcompressed?