At room temperature $(20C),$ a $0\mathrm{.}5mm$ gap exists between the ends of the rods shown below.

Later when the temperature reaches $140C,$ determine the axial stress in the aluminium rod

and its exact length. For the aluminium rod, $A=2000m{m}^2,E=70K\frac{N}{m}{m}^2,$

$=23\frac{{10}^{-6}}{}C.$ For the stainless steel rod, $A=800m{m}^2,E=190K\frac{N}{m}{m}^2,=18\frac{{10}^{-6}}{}C.$