A round bar having a length of 1.2 m and a diameter of 6 mm is made of an aluminum alloy for which the stressstrain diagram can be described mathematically by the following equation:
![1353_a3807905-fe23-45ab-8eb1-e277965fd3c0.png](https://secure.tutorsglobe.com/CMSImages/1353_a3807905-fe23-45ab-8eb1-e277965fd3c0.png)
in which σ has units of megapascals (MPa). The shape of this stress-strain diagram is shown in the figure. The bar is axially loaded by tensile forces P = 12.5 kN, after which the loads are removed. What is the permanent set of the bar?
![50_48b7b9e4-2515-43e3-b1b6-d1f21d3d590e.png](https://secure.tutorsglobe.com/CMSImages/50_48b7b9e4-2515-43e3-b1b6-d1f21d3d590e.png)