1. The problem statement, all variables and given/known data I have a bloc sitting on a horizontal table, and we shoot a ball through it. The speed right before entering the block is v and the speed when it exits the block is v/2. I need to prove that the fraction of the initial energy that is lost due to heat is 3/4 - γ/4, where γ is mass of ball/mass of block (γ<1) 2. Relevant equations Conservation of momentum 3. The attempt at a solution I know that usually kinetic energy is given by 1/2 mv^2, so then the kinetic energy of the ball once it exits the block will be 1/8 mv^2. I am not sure how to begin with this question.