Solution:

Radius $r = 5 \text{ cm} = 0.05 \text{ m}$, Time period $T = 0.2\pi$. Angular velocity $\omega = \frac{2\pi}{T} = \frac{2\pi}{0.2\pi} = 10 \text{ rad/s}$. Centripetal acceleration $a = \omega^2 r = (10)^2 \times 0.05 = 100 \times 0.05 = 5 \text{ m/s}^2$.