고체역학 (Beer) — Stress and Strain—Axial Loading: Problem 2.8

2.8 Two gage marks are placed exactly 10 in. apart on a 1/2-in.-diameter aluminum rod with \(E = 10.1 \times 10^6\) psi and an ultimate strength of 16 ksi. Knowing that the distance between the gage marks is 10.009 in. after a load is applied, determine (a) the stress in the rod, (b) the factor of safety.