1. The problem statement, all variables and given/known data I have two particles in an accelerator approaching eachother with a relative speed of 0.880c. The particles travel at the same speed as measured in the laboratory. I have to find the velocity of each particle. 3. The attempt at a solution Ok, I use the transformation of velocities: u'_x = (2*0.880c)/(1-(-(0.880c)^2/c^2) - since v_1 = -v_2. I get 0,99c, but apparently it must equal 0,597c?!