A common unit of energy used in atomic and nuclear physics is the electron volt (eV), the energy acquired by an electron in falling through a potential difference of one volt; 1 MeV = 106 eV = 1.602 X 10–13 J. In these units, the mass of an electron is mec2 = 0.511 MeV and that of a proton is mpc2 = 938 MeV. Calculate the kinetic energy and the quantities β and y for an electron and for a proton each having a momentum of 100 MeV/c. Show that the electron is “relativistic” whereas the proton is “non-relativistic”.