$[3$ points$]$ The angular velocity of a $755-g$ wheel $15\mathrm{.}0$ cm in diameter is given by the equation $(t)=(2\mathrm{.}00ra\frac{d}{s^2})t+(1\mathrm{.}00ra\frac{d}{s^4})t^3.$

$($a$)$ Through how many radians does the wheel turn during the first $2\mathrm{.}00$ s of its motion?

$($b$)$ What is the angular acceleration $($in $ra\frac{d}{s^2})$ of the wheel at the end of the first $2\mathrm{.}00$ s of its motion?