2. Relevant equations
PE=.5kx^2
F=-kx

3. The attempt at a solution

I honestly just dont know how to approach a problem where you have to find both the spring constant and the compression distance….

Ive tried employing conservation of momentum, ive tried working backwards with M1…

Im pretty sure I need to find an equation that would solve for either K or x and then use that to find the other value.

Am I on the right track?