Question

The coefficient of linear expansion of steel is  

12 × 10^-6/C°. A railroad track is made of individual rails of steel 1.0 km in length. By what length would these rails change between a cold day when the temperature is –10 °C and a hot day at 30 °C?

Answer 1

$\Delta l=l_0\cdot\alpha\Delta t=1000\cdot12\cdot10^{-6}\cdot 40=0.48\ (m)$