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

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