고체역학 (Beer) — Torsion: Problem 3.79

3.79 A 1.5-in.-diameter steel shaft of length 4 ft will be used to transmit 60 hp between a motor and a pump. Knowing that \(G = 11.2 \times 10^6\) psi, determine the lowest speed of rotation at which the stress does not exceed 8500 psi and the angle of twist does not exceed 2°.