(i) consider a particle with 4-momentum p in the vicinity of an observer with four-velocity u prove that if the particle goes through the observer's laboratory the energy of the particle as measured by the observer is m e where v2 is the squared magnitude of the projectile's 3-velocity in the laboratory frame. do we need to assume we are in minkowski space to derive this result? explain briefly. (ii) use a binomial expansion to derive the non-relativistic limit of the above expression for e and identify the physical significance of the two terms that are summed