Answer
Example 1: $a=288m/s^2$
Example 2: $a=0$
Example 3: $a=2.94m/s^2$
Work Step by Step
The magnitude of the centripetal acceleration can be calculated with the following formula: $$a=\frac{v^2}{r}$$
(a) Example 1: speed $v=12m/s$, radius $r=0.5m$
$$a=\frac{12^2}{0.5}=288m/s^2$$
(a) Example 2: speed $v=35m/s$, radius $r$ infinitely large
$$a=\frac{v^2}{r}=0$$
(a) Example 1: speed $v=2.3m/s$, radius $r=1.8m$
$$a=\frac{2.3^2}{1.8}=2.94m/s^2$$
