Initially a wheel is turning at $65 \mathrm{rad} / \mathrm{s}$. 'Ihereafter, angular acceleration is given by $\alpha=(-10-5 t) \mathrm{rad} / \mathrm{s}^{2}$ where $t$ is the elapsed tine.
(a) Find its angular speed at $t=3.0 \mathrm{~s}$.
(b) With what angular displacement does it turn in these $3 \mathrm{~s}$ ?