A source$-$free RC circuit has R $=4$ kQ and C $=22$ uF$,$ and with the knowledge that v$(0)=5$ V$,($a$)$ write an expression for v$($t$)$ valid for t $>0$; $($b$)$ compute v$($t$)$ at t$=0,$ f$=50$ ms$,$ and tf $=500$ ms; and $($c$)$ calculate the energy stored in the capacitor at t$=0,$ t$=50$ ms$,$ and t $=500$ ms$.$