고체역학 (Beer) — Stress and Strain—Axial Loading: Problem 2.132

2.132 A polystyrene rod consisting of two cylindrical portions AB and BC is restrained at both ends and supports two 6-kip loads as shown. Knowing that \(E = 0.45 \times 10^6 \text{ psi}\), determine (a) the reactions at A and C, (b) the normal stress in each portion of the rod.