Steel wire of lenght ' L ' at $40^{\circ} \mathrm{C}$ is suspended from the ceiling and then a mass ' m ' is hung from its free end. The wire is cooled down from $40^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ to regain its original length ' L '. The coefficient of linear thermal expansion of the steel is $10^{-5} /{ }^{\circ} \mathrm{C}$, Young's modulus of steel is $10^{11} \mathrm{~N} / \mathrm{m}^2$ and radius of the wire is 1 mm . Assume that $\mathrm{L} \square$ diameter of the wire. Then the value of ' m ' in kg is nearly