1. The problem statement, all variables and given/known data In a certain reference frame, a particle with momentum of 7 MeV/c and a total energy of 9 MeV. Determine the mass of the particle. I did not mistype this problem, this is the way it appears on my assignment. 2. Relevant equations Total Relativistic Energy: E^2=p^2c^2+(mc^2)^2 3. The attempt at a solution I figured that since I am given the total energy of the particle and the momentum of the particle, I could plug those values in and solve for m. However, this gives me the wrong answer. I also tried taking both values given and converting them to joules so that my answer for mass would be in kilograms and then converting to eV, but that didn't work either. Any suggestions?