Answer
$a = 4.1~m/s^2$
Work Step by Step
We can find an expression for the person's speed:
$v = \frac{(2\pi)(15~m)(5)}{60~s} = (2.5\pi)~m/s$
We can find the magnitude of the acceleration:
$a = \frac{v^2}{r}$
$a = \frac{(2.5\pi~m/s)^2}{15~m}$
$a = 4.1~m/s^2$
