Simple Harmonic Motion: Calculating Speeds of Blocks with a Compressed Spring

[pezola]

Homework Statement

A 15.8 kg block and a 31.6 kg block are resting on a horizontal frictionless surface. Between the two is squeezed a spring (spring constant = 1868 N/m). The spring is compressed by 0.152 m from its unstrained length and is not attached permanently to either block. With what speed does each block move away when the mechanism keeping the spring squeezed is released and the spring falls away?

The Attempt at a Solution

This is a sample problem for the final exam. Please explain the process, I'm not just looking for a numerical answer.

 

[Doc Al]

Show what you've done so far and point out where you are stuck.

Hint: What's conserved?

(This isn't a SHM problem.)