고체역학 (Beer) — Transformations of Stress and Strain: Problem 7.111

7.111 A steel penstock has a 36-in. outer diameter and connects a reservoir at A with a generating station at B. Knowing that the specific weight of water is $62.4 \text{ lb/ft}^3$ and that the allowable normal stress in the steel is $12.5 \text{ ksi}$, determine the smallest thickness that can be used for the penstock.