1. The problem statement, all variables and given/known data What thickness of copper is required to stop a 500 MeV/c proton? 2. Relevant equations E=(m^2+p^2)^1/2 3. The attempt at a solution So I have been to some websites and trying to google this- and everyone is using charts and looking of the value of the range in a material. First, I cannot find the chart for copper and protons. I can convert the momentum to energy - but thats all I got. How can I solve this problem? Thanks!