IIT JEE Advanced 2011 Paper 1

Steel wire of length L at 40°C is suspended from the ceiling and then a mass m is hung from its free end. The wire is cooled down from 40°C to 30°C to regain its original length L. The coefficient of linear thermal expansion of the steel is 10−5∕°C, Young’s modulus of steel is 1011N∕m2 and radius of the wire is 1 mm. Assume that L >> diameter of the wire. Then the value of m in kg is nearly ______.