A pendulum is suspended by a string of length 250 cm . The mass of the bob of the pendulum is 200 g . The bob is pulled aside until the string is at $60^{\circ}$ with vertical as shown in the figure. After releasing the bob. the maximum velocity attained by the bob will be $\_\_\_\_$ $\mathrm{ms}^{-1}$. (if $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ )