Work Power And Energy

The velocity at which 6 kg mass (shown in figure) strikes the ground when it is released from a height of 6 m above the ground is $\_\_\_\_$ $\mathrm{m} / \mathrm{s}$. Assume pulley is massless and string is light and inextensible. (Take $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ )