Question $5$

A small $2\mathrm{.}4m$ high retaining wall is constructed of vertical wooden planks as shown by ABC in the Figure. The planks are $200mm$ wide and simply supported at B and C by a horizontal steel beam and a concrete footing respectively. The steel beam is $0\mathrm{.}6m$ from the top of the wall. The soil pressure against the wall is assumed to vary linearly from zero at the top $($point A$)$ to $15$kPa at the bottom $($point C$).$ Calculate the maximum bending moment in the plank.