$23.$ An electron is to be accelerated through a uniform electric field having a strength of $2\mathrm{.}00$x$106$ V$/$m through a distance of $0\mathrm{.}400$ m$.$

$($a$)$ What energy in keV is given to the electron?$$ If the electron was initially at rest, what is the final velocity of the electron?

$($b$)$ Replace the electron with a proton. $$What energy in keV is given to the proton?$$ If the proton was initially at rest, what is the final velocity of the proton?