Question

A rail road of length 20m is heated through 30°c to 100°c. calculate the gap between the rails

Answer 1

Given:

$l_0=20\:\rm m$

$\Delta T=70^\circ$

$\alpha=12*10^{-6}\rm\:K^{-1}$

The change in the linear dimension of a rail due thermal expansion

$$\Delta l=l_0\alpha\Delta T$$

Hence, the gap between rails

$$\Delta l=20*12*10^{-6}*70=0.0168\:\rm m=1.68\: cm$$