1. The problem statement, all variables and given/known data 2. Relevant equations Kinetic energy = Ke = (1/2)(mv^2) (joules - J) where m = mass (kg) v = velocity (m/s) 3. The attempt at a solution What I was thinking was that the kinetic energy is divided uniformly over the distance d and hence Average crush force = mv^2 / 2d But I don't know how to prove that. Of course I could try to explain it with words, but I don't feel that it is enough. Thank you in advance.