1. The problem statement, all variables and given/known data okay i have attached the question and what i simply have to do is plot the stress-strain graph. 2. Relevant equations strain = extension/initial length stress=force/area 3. The attempt at a solution Okay, i calculated the strain by dividing each of the extensions by 30mm which is correct right?? But now i need to calculate the stress in order to plot the graph which is simply the force divided by the area however it says the diameter reduces down from 12mm to 11.74mm. at fracture. So then which one do i use to calculate the stress the 12 or 11.74. how do i know exactly at what force the diameter changes??or do i just ignore that and find the stress by dividing the force by 12mm---0.0012metres?