No, its energy. There is an engineering test called a http://www2.umist.ac.uk/material/research/intmic/features/charpy/notes.htm that takes into account all the factors that Halls mentioned and calls the energy required to break a sample "impact toughness". By using a heavy pendulum to break a test sample, the energy required to break it can be measured simply by using the difference in the height of the pendulum between the upstroke and the downstroke and applying the potential energy equation.cscott said:Lets say I have a human bone, and I'm putting weights on it until it snaps, then I have another bone but let the weights fall onto the bone. I'm assuming the second bone will break with less weight because we're letting the weights fall. It is momentum that's involved here? What equations would I be working with?