Answer:
[tex]l=L\alpha(T_c-T)[/tex]
Explanation:
L = Initial length of segment = 79 m
T = Normal temperature = [tex]20^{\circ}\text{C}[/tex]
l = Width to be left for expansion
[tex]\alpha[/tex] = Coefficient of linear expansion of the material = [tex]12\times 10^{-6}^{\circ}\text{C}^{-1}[/tex]
[tex]T_c[/tex] = Maximum temperature = [tex]39.5^{\circ}\text{C}[/tex]
[tex]\Delta T[/tex] = Change in temperature = [tex]T_c-T[/tex]
The expression of linear expansion is given by
[tex]l=L\alpha\DeltaT\\\Rightarrow l=L\alpha(T_c-T)[/tex]
The expression for the minimum gap distance l the engineers must leave for a track rated at temperature [tex]T_c[/tex] is [tex]l=L\alpha(T_c-T)[/tex]