Concept Application $2\mathrm{.}15$

If the load $P$ applied to the rod$-$tube assembly of Concept Application $2\mathrm{.}14$ is increased from zero to $5\mathrm{.}7$ kips and decreased back to zero, determine $($a$)$ the maximum elongation of the assembly and $($b$)$ the permanent set after the load has been removed. $($Please re$-$work Concept Application $2\mathrm{.}15$ so the load should increase from zero to $6\mathrm{.}0$ kips then decreased back to zero.$)$