1. The problem statement, all variables and given/known data a proton with kinetic energy 10GeV collides with a proton at rest. 1 proton goes off with an angle of 45 degrees relative to the incoming proton. Find the velocity of both protons after the collison. This is an ellastic collision. E(initial) = 938 mev i honestly dont know where to start off but heres my attempts at a answer 2. Relevant equations 3. The attempt at a solution E=(MC^2)/(1-(v/c)^2)^1/2 V/c= (1-((mc^2)/(E^2)))^1/2 V= .99632c V= v1 cos (30) + v2 cos(theta) v1 sin (30) + v2 sin (theta) E = E1 + E2 10.938 gev = .938 gev/ (1-(v1/c)^2))^1/2 + .938gev/(1-(v2/c)^2)^1/2 substitute and get the answer v1 is .00458 and v2 is .49780 however these answers dont work when put back into the equations..