$6\mathrm{.}5$ Consider the two$-$steel rod assembly shown. $T_{12}=160F$ and $T_{23}=110F.$

They were both initially at $70F.$

Compute

$($a$)$ the force in each rod,

$($b$)$ the stress in each rod,

$($c$)$ the displacement of point $2.$

$E=30{10}^6,=7{10}^{-6}\frac{1}{}F,A_{12}=3i{n}^2,A_{23}=2i{n}^2$