(Solved): (12-2) Figure Q12 shows a truss jib structure with a roller-pivot at A and a hinge at B (illustrati ...

(12-2) Figure Q12 shows a truss jib structure with a roller-pivot at A and a hinge at B (illustration not drawn to scale). The horizontal members are 3 metres long and the vertical members are 4 metres long. The structure is loaded at I with a horizontal force of \( X=11 \mathrm{kN} \) and a vertical dowrward force of \( Y=40 \mathrm{kN} \). Find the internal force experienced in the member \( \mathrm{IG} \) in terms of \( \mathrm{kN} \) to 1 d.p. State your answer in the box, in your answer use the convention a member which has a negative value is in compression.