s of copper as shown in the 3 below. Thin spacers provide a s s. The copper bars have ectional dimensions 12 mm by 50m has dimensions 25 mm 6 50 mm. Deter mine the shear 11m if the ter mperature is meed by 40'C. (20 marks) (For copper. E.=124 GPa and a =20x10*/C, for aluminium, E.= 69 GPa and a,=26x10/C.) Copper bar Aluminum bar Copper bar Figure 3 Useful formula Axial hood: Normal stress 6 = ent: 6 = FL EA a = An) & = wlAT)L