QS@$).$Two parallel walls $6$ m apart are stayed together by a steel rod $25$ mm diameter passing through metal plates and nuts at each end. The nuts are tightened home, when the rod is at a temperature of $100$C$.$ Determine the stress in the rod, when the temperature falls down to $60$C$,$ if the ends do not yield, and Take Modulus of elasticity $=200$ G Pa and Coefficient of linear expansion $=12*10^-6/$C$..$Two parallel walls $6$ m apart are stayed together by a steel rod $25$ mm diameter passing through metal plates and nuts at each end. The nuts are tightened home, when the rod is at a temperature of $100$C$.$ Determine the stress in the rod, when the temperature falls down to $60$C$,$ if the ends do not yield, and Take Modulus of elasticity $=200$ G Pa and Coefficient of linear expansion $=12*10^-6/$C