PART $2$ :: Calculate the Section Modulus $($S$)$ needed for the bridge structural member shape that will carry the loads

listed below. Next consult your textbook $(7$the edition$)$ Appendix A$-7($e$)$ I$-$beam IPE$-$Shapes, and choose the lightest

shape that will carry the load. Write down the letter of the chosen shape $($a$-$r$).$ Be sure to show your hand calculations.

NOTE: Do not use factor of safety