1. The problem statement, all variables and given/known data In reference frame S', two protons, each moving at .500c, approach each other head-on. a) calculate the total kinetic energy of the two protons in frame S'. b) Calculate the total kinetic energy of the protons as seen in the reference frame S, which is moving with one of the protons. 2. Relevant equations E = mc^2 + K K = γ1/2mv^2 Proton rest mass = 938 MeV/c^2 3. The attempt at a solution So for part A I just found the kinetic energy of one of the protons given by γ(1/2)mv^2 (1.1547)(1/2)(938)(.25) * 2 = 270 MeV.. and the back of the book says 290 MeV.. but this textbook is known for having a lot of wrong answers, can anyone verify whether I am correct or incorrect?