This is my first time here! Thanks for the help in advance. The staples inside a stapler are kept in place by a spring with a relaxed length of 0.115 m. If the spring constant is 45.0 N/m, how much elastic potential energy is stored in the spring when its length is 0.145 m? Answer in units of J. I know I have to use F=kx (maybe), but what's confusing me is the potential energy part. How do I fit that into finding the answer?