following data was obtained from a tensile test of steel. The test specimen was 15mm in diameter and 50 mm in length
Load (kN) Elongation(mm)
5 0.005
10 0.015
30 o.048
50 0.084
60 0.102
64.5 0.109
67 0.119
68 0.137
69 0.160
70 0.229
72 0.300
76 0.424
84 0.668
92 0.965
100 1.288
112 2.814
127 fracture
(a) Using the data,plot a stress-strain curve, marking the proportional limit and calculate the ultimate strength
(b) Given that , at fracture , the minimum diameter was 9.5 mm, calculate the reduction in cross-sectional area, expressing the answer as a percentage of the original cross-sectional area.