I have plotted Force vs Stress graph. I want to know: 1- What does the slope represent and what does it indicate? 2- Can you find what is the material used? If cannot then why not?

Question 7- A technician measured the hardness of the steel bar two times. For the first time, he measured the hardness. He heated the steel bar to a high temperature and wait for the steel bar to decrease the temperature to room temperature. The technician measured the hardness of the steel bar again. (a) Did the technician get the same hardness in both measurements? Answer: (b) Please explain your point of view.

In a tensile test for an aluminum alloy, the sample is 2 inches long and 0.5 inches in diameter. The proportional portion of the tension stress-strain diagram for an aluminum alloy is shown below.  It the diameter change of the sample was also monitored during the above test, and it was found that the lateral strain of the sample is 1/3 of its axial longitudinal strain, what is the Poisson' ratio of the material under test: ___. Calculate your answer to 2 decimal place.

41) A 19mm diameter cylindrical rod is subject to extreme loading. It must withstand a 75000 N tensile force without yielding. The material you are given has a 270MPa yield strength, and will meet the design requirements True False