1. The problem statement, all variables and given/known data A pulley containing only a single mass, m, is hanging vertically from a mass with spring constant k. Find the period of vertical oscillation for the mass. Explanation in terms of energy and energy conservation is preferred. 2. Relevant equations Ay, there's the rub. You are supposed to find the spring's potential energy in terms of y (the height of the mass) and then use T=2*pi√(m/k) once you find the "true" k that corresponds with the mass (the second derivative of the potential energy U) 3. The attempt at a solution None worth noting. I know for sure that all of my attempts are terrible. If you need a closer look its from the lightandmatter.com textbook "Simple Nature", Chapter 2, question #35.