Problem $4$ Treat the strut AB as a cable with diameter $12$ mm and the post CD has a diameter of $40$ mm $.$

$($a$)$ Draw a free body diagram of the beam AC by removing the cable and the post support. Assume the bar is thin, and that the weight is negligible.

$($b$)$ Find reaction forces on the beam AB supplied by the cable and post.

$($c$)$ Find the axial stress $\backslash (\backslash$sigma $\backslash )$ in both the cable AB and post CD$.$ Report whether this axial stress is either causing tension or compression.