An electron is accelerated from rest through a potential difference that has a magnitude of $3\mathrm{.}00$ x $10^7$ V$.$ The mass of the electron is $9\mathrm{.}11$ x $10^-31$ kg$,$ ad the negative charge of the electron has a magnitude of $1\mathrm{.}60$ x $10^-19$ C$.($a$)$ What is the relativistic kinetic energy $($in joules$)$ of the electron? $($b$)$ What is the speed of the electron? Express your answer as a multiple of c$,$ the speed of light in a vacuum.