1. The problem statement, all variables and given/known data A spring with stiffness k and unstretched length L is stretched so the elongation is d = x2 - L. A force is applied to make the final length of the spring x2. What is the work done by the force in terms of d? 2. Relevant equations W = F * d = F*dx d = x2 - L F = k*dx 3. The attempt at a solution Assuming W = F*dx and F = k*dx, then I derived F = k(x2 - L) = k*d And plugging F back into the work equation, I got W = (kd)*d which is W = kd^2. However, isn't the actual equation for work done by a spring W = (kx^2)/2? I can't seem to find where I missed the factor of 1/2. Any help greatly appreciated!