Rigid bar ABCD is loaded and supported as shown.

Bars $(1)$ and $(2)$ are unstressed before the load $P$ is

applied. Bar $(1)$ is made of bronze $[E=100$GPa $]$

and has a cross$-$sectional area of $510m{m}^2.$ Bar $(2)$

is made of aluminum $E=70$GPa and has a cross$-$

sectional area of $980m{m}^2.$ After the load $P$ is

applied, the force in bar $(2)$ is found to be $15$ kN $($in

tension$).$ Assume $a=0\mathrm{.}4m,b=1\mathrm{.}1m,c=0\mathrm{.}4m,L_1=$

$0\mathrm{.}5$ m $,$ and $L_2=0\mathrm{.}8m.$ Determine

$($a$)$ the stresses in bars $(1)$ and $(2).$ By convention,

tensile stresses are positive and compressive

stresses are negative.

$($b$)$ the vertical deflection of point A$.$ The vertical

deflection is positive if downward and negative if

upward.

$($c$)$ the load $P.$