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A steel railroad $(E=200$GPa,${}_s=11\mathrm{.}7\frac{{10}^{-6}}{}C)$ in Lytton, BC was initially

constructed in May $1950$ at a temperature of $6C.$ Each individual rail in the railroad

is $10$ m long. Due to severe anthropogenic climate change, Lytton has started to see

temperatures exceeding $40C$ every summer. In fact, Lytton saw the highest

temperature ever recorded in Canada on June $29,2021$ when a temperature of $49C$

was reached.

Determine the normal stress in the rail when the temperature reaches $49C,$ if the

individual rails were welded together to form one big continuous track in May $1950.$

$[$Bonus $5$ marks$]$ As a climate$-$conscious engineer in the $1950$s$,$ you recommend that

the rails are separated with $3-mm$ gaps between them instead of being welded. What

is the normal stress in the rail when the temperature reaches $49C$ in this situation?