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 2. Relevant equations So basically i started with Ki + Ui = Kf + Uf and then manipulated adding in the equation for the spring constant, k and ended up with: rad[(2Mg +m)k/m)] * d but its totally wrong help please!