QUESTION $3(10$ marks$)$

For a simply$-$supported beam made of material having an allowable tensile and

compressive stress of $({}_{\text{a}\text{l}\text{l}\text{o}\text{w}}{)}_t=120$MPa and $({}_{\text{a}\text{l}\text{l}\text{o}\text{w}}{)}_c=100$MPa, respectively, determine

the maximum allowable internal moment that can be applied to the beam. Also draw the

bending stress distribution on the beam cross$-$section as a result of that moment. The

beam cross$-$section is shown in Figure $3.$