고체역학 (Beer) — Pure Bending: Problem 4.121

4.121 An eccentric force P is applied as shown to a steel bar of 25 × 90-mm cross section. The strains at A and B have been measured and found to be \(\epsilon_A = +350 \mu\), \(\epsilon_B = -70 \mu\). Knowing that \(E = 200 \text{ GPa}\), determine (a) the distance \(d\), (b) the magnitude of the force \(P\).