Answer:
66.4767 m
Explanation:
[tex]L_0[/tex] = Original length of power line = 145 km
[tex]\alpha[/tex] = Coefficient of linear expansion = [tex]1.62\times 10^{-5}\ /^{\circ}C[/tex]
Initial temperature = 13.7°C
Final temperature = 42°C
Change in length of a material is given by
[tex]\Delta L=\alpha L_0\Delta T\\\Rightarrow \Delta L=1.62\times 10^{-5}\times 145000\times (42-13.7)\\\Rightarrow \Delta=66.4767\ m[/tex]
The change in length will be 66.4767 m