Question $5$:

At the proportional limit$,$ a $20$ mm thick $70mm$ wide bar elongates $6$ mm under an

axial load of $400$ kN $.$ The bar is $1\mathrm{.}8$ m long. If Poisson's ratio is $0\mathrm{.}3$ for the material,

determine:

$($a$)$ The modulus of elasticity.

$($b$)$ The proportional limit$.$

$($c$)$ The change in each lateral dimension.