8. Designing an efficient and robust windmill is important for converting wind energy to electricity. Suppose a windmill fan is supported by a cylindrical rod 350 mm long, having a diameter of 13.5 mm, subjecting a tensile load. (a) If the rod is to experience neither plastic deformation nor an elongation (along the applied stress) of more than 0.6 mm when the tensile load is 42,000 N, please select suitable materials candidates for this purpose. Justify your answer. (b) Using Brass alloy as the windmill fan, calculate the change in diameter of the fan under the same tensile load. Will the diameter increase or decrease? (15 pt) Modulus of Elasticity (GPa) 70 Poisson's Ratio Tensile Strength (MPa) Yield Strength (MPa) Material 255 420 0.33 100 345 420 0.34 Aluminum alloy Brass alloy Copper Steel alloy 110 250 290 0.34 207 450 550 0.3