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 /0.048
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.