Question

Sian wants to keep her large collection of books in an alcove in her sitting room. The alcove is 1.2 m wide and you offer to install a set of pine shelves, each 1.2 m long, supported at their ends on small brackets screwed into the wall. You guess that shelves measureing 0.02 m deep by 0.20 m wide will work. However, professional integraity demands that you calculate the maximum stress and deflection first. For pine, Young’s modulis E ≈ 10 G m-2 and the tensile strength σy ≈ 60 MN m-2. A book 0.04 thick wieghs about 0.8 kg.