A steel rod with \( y=2.0\times10^{11}\ \text{Nm}^{-2} \) and \( \alpha=10^{-5}\,^\circ\text{C}^{-1} \) of length \( 4\,\text{m} \) and area of cross-sectional \( 10\,\text{cm}^2 \) is heated from \( ^\circ\text{C} \) and \( 400^\circ\text{C} \) without being allowed to extend. The tension produced in the rod is \( x\times10^5\,\text{N} \) where the value of \( x \) is:
