Answer
$a=17.77m/s^2$
Work Step by Step
The magnitude of the total acceleration is $a=\sqrt{a_T^2+a_c^2}$
We have angular speed $\omega=3rad/s$ and radius $r=1.25m$, so $$a_c=r\omega^2=11.25m/s^2$$
We have angular acceleration $\alpha=11rad/s^2$ and radius $r=1.25m$, so $$a_T=r\alpha=13.75m/s^2$$
Therefore, $$a=17.77m/s^2$$
