An alpha particle $($g $=+2$e$,$ m $=4\mathrm{.}00$ u$)$ travels in a circular path of radius $5\mathrm{.}07$ cm in a uniform magnetic field with B $=1\mathrm{.}01$ T$.$ Calculate

$($a$)$ its speed, $($b$)$ its period of revolution, $($c$)$ its kinetic energy, and $($d$)$ the potential difference through which it would have to be accelerated to achieve this energy.