3. (a) (i) List the important points on a stress-strain diagram. (ii) When you conduct a tensile test experiment of a ductile material and acquire the associated raw data, are you going to plot the engineering or true stress-strain curve (or both), and why? (b) The figure below shows the stress-strain diagram and the cross-sectional diameter of a material. The length of the shown specimen is 50 mm. (i) Determine the elongation of the specimen if P is equal to 100 kN. (ii) Determine the permanent elongation of the specimen if P = 150 kN is applied and then released.