1. The problem statement, all variables and given/known data Write the momentum four vector of a particle that has: Rest mass = 80 Gev/c^2 Energy = 100 Gev and moves along the z axis.What is its speed as a fraction of the speed of light. 2. Relevant equations E^2 = p^2c^2 + m^2C^4 3. The attempt at a solution Momentum four vector - (0, 0, (3*10^10)v, 1.1*10^15) in units of Gev/c The speed i got was v/c = 1.22*10^-34 but when I double check it, it doesn't seem to match. I'm not sure where I'm going wrong, is my four momentum vector wrong?