$3\mathrm{.}32$ A simple mechanical system is shown in Fig. $3\mathrm{.}58($a$).$ The parameters are $k=$ spring constant, $b=$ viscous friction constant, $m=$ mass. A step of $2$ N force is applied as $F=21(t)$ and the resulting step response is shown in Fig. $3\mathrm{.}58($b$).$ What are the values of the system parameters $k,b,$ and $m?$

$($b$)$