Thermal conductivity of a rod of length l and uniform cross section area A varies with temperature as $K=\frac{K_0}{a+bT}$ ,where $K_0$ and a and b are constants. The temperature of two ends of rod are $T_{1 }\& T_2$. Find the rate of flow of heat across the rod

There is some change in length of a steel rod when a $33000 \mathrm{N}$ tensile force is applied to it. The area of cross-section of the rod is ${10}^{-3 } {\mathrm{m}}^2$. The change in temperature required to produce the same elongation, if the steel rod is heated, is

(The modulus of elasticity is $3\times {10}^{11} \mathrm{N} {\mathrm{m}}^{-2}$ and the coefficient of linear expansion of steel is $1.1\times {10}^{-5} °{\mathrm{C}}^{-1}$)