$(20$ points$)$ A bar $OA,$ pinned at $O,$ spins in circles on a horizontal table. The figure shows $OA$

as viewed from above. Given the angular position of the bar $(t)=\frac{1}{2}{t}^2$ and that the length of

the bar is $L=5ft,$ find the magnitude of the velocity and acceleration at point A when $=5$

radians $($use curvilinear motion techniques$).$ Make sure to draw a clear axis.