1. The problem statement, all variables and given/known data Determine how accurately you will need to measure the speed of a particle that has energy 2 GeV to determine whether it is a pion (mass = 0.14 Gev/c^2) or a Kaon (mass = 0.49 Gev/C^2). *This question is in a relativity section, so I'm assuming relativistic equations are neccesary* 2. Relevant equations [tex] E^2 = (p^2)(c^2) + (m^2)(c^4) [/tex] [tex] p = (\gamma)mv [/tex] 3. The attempt at a solution I started by substituting [tex] p= (\gamma)mv [/tex] into the other equation so velocity can be related to mass, but I'm lost as to what the basic approach to this problem would be.