Answer
(a) $\alpha=2.03\frac{rad}{s^2}$
(b) greater than 2.03$\frac{rad}{s^2}$.
Work Step by Step
(a) We know that
$\alpha=\frac{a}{r}$
$\alpha=\frac{1}{r}\frac{\Delta v}{\Delta t}$
$\alpha=\frac{8.90-0}{0.360\times 12.2}$
$\alpha=2.03\frac{rad}{s^2}$
(b) $\alpha=\frac{a}{r}$
The above equation shows that angular acceleration and radius are inversely proportional, hence if the radii of the tires were smaller then angular acceleration would be greater than 2.03$\frac{rad}{s^2}$.
