1. The problem statement, all variables and given/known data You have been asked to design a "ballistic spring system" to measure the speed of bullets. A spring whose spring constant is k is suspended from the ceiling. A block of mass M hangs from the spring. A bullet of mass m is fired vertically upward into the bottom of the block. The spring's maximum compression d is measured. Find an expression for the bullet's speed vb. Express your answer in terms of the variables m, M, k, d, and constant g. 2. Relevant equations Us=0.5kd2 Ug=mgh K=0.5mv2 3. The attempt at a solution I just have absolutely no idea how to approach this problem. I know I am supposed to have an attempt at a solution but I've never felt so lost on a physics problem before. Please help!