A fine steel wire of length 4 m is fixed rigidly in a heavy brass frame as shown in figure. It is just taut at 20oC. Find the tensile stress developed in steel wire (in x106 Nm-2) if whole system is heated to 120oC.  (Given αbrass =1.8×10−5∘C−1, αsteel =1.2×10−5∘C−1, Ysteel =2×1011Nm−2,Ybrass =1.7×107Nm−2