A 0.507-kg block is attached to a horizontal spring that is at its equilibrium length, and whose force constant is 15.1 N/m. The block rests on a frictionless surface. A 0.0500 kg wad of putty is thrown horizontally at the block, hitting it with an initial speed of 2.53 m/s and sticking. How far does the putty-block system compress the spring?