A stone of mass $1 \mathrm{kg}$ tied to a light inextensible string of length $L=\frac{10}{3} \mathrm{m}$ is whirling in a circular path of the radius $L$ in the vertical plane. If the ratio of the maximum tension to the minimum tension in the string is $2$. What is the speed of stone (in $\mathrm{m} {\mathrm{s}}^{-1}$) at the highest point of the circle? (Taking $\mathrm{g}=10 \mathrm{m} {\mathrm{s}}^{-2}$)