$2\mathrm{.}3\mathrm{.}5.[$Level $1]$ The lower portion of a fire ladder $(\frac{?}{\text{b}\text{a}\text{r}}(OA))$

rotates about its hinge $O$ at ${}^{}=0\mathrm{.}05ra\frac{d}{s}$ and ${}^{}=0\mathrm{.}04ra\frac{d}{s^2}.$

The upper portion extends out from the lower portion such

that $c^{}=0\mathrm{.}4\frac{m}{s}$ and $c^{}=0\mathrm{.}1\frac{m}{s^2}.$ Determine the velocity

and acceleration of $B$ with respect to $e_r,e_{}$ as well as $i,j$ for

$=\frac{}{6}$rad and $c=2m.$