Gravitational acceleration on the surface of a planet is $$\frac{\sqrt{6}}{11} g$$, where g is the gravitational acceleration on the surface of the earth. The average mass density of the planet is $$\frac{2}{3}$$ times that of the earth. If the escape speed on the surface of the earth is taken to be 11 $$kms^{-1}$$, the escape speed on the surface of the planet in $$kms^{-1}$$ will be