A surveyor uses a steel tape that is exactly 50 m long at a temperature of 20°C.What is the length on a hot summer day when the temperature at 35°C.[Cofficeant of linear expression of steel is 1.2×10^-5 mk^-1]

$\begin{aligned} L & =L_{0}(1+\alpha t) \\ L_{20} & =L_{0}\left(1+1.2 \times 10^{-5} \times(20+273)\right) \\ L_{0} & =49.825 \\ L_{35} & =L_{0}\left(1+1.2 \times 10^{-5} \times(35+273)\right) \\ & =50.009 \mathrm{~m}\end{aligned}$