Hookes Law (Stress equals Young’s Modulus times Strain; or s=Ee) is valid for both linear tensile behaviour and torsion (or shear) as well (e.g. t=Gg). Imagine a shear test of annealed, mild steel (e.g. AISI 1020). It is sheared until it just starts to yield (normal yield is about 36 ksi). How many degrees of shear will have been applied? Note that the angle of shear approximates the value of shear for small, elastic deformations. Recall, G is the torsion (or shear) modulus (about 10 msi for 1020 steel). Also, yield in shear is about half that in tension.