1. The problem statement, all variables and given/known data There is a spring attached to a hanging block by a rope over a pulley, with a stop on the other end. Using basic physic principles, determine the relationship between spring extension and weight of the block. 2. Relevant equations F=-kd w=mg 3. The attempt at a solution I know that if the system is in equilibrium, the sum of forces acting on the block/spring should be zero. Also, since the force of the rope on the block and the force of the rope on the spring are third law pairs, they should be equal in magnitude but in opposite directions. Not quite sure where to go from here though.