고체역학 (Gere) — Torsion: Problem R-3.6

R-3.6 A steel tube with diameters \(d_2 = 86 \text{ mm}\) and \(d_1 = 52 \text{ mm}\) is twisted by torques at the ends. The diameter of a solid steel shaft that resists the same torque at the same maximum shear stress is approximately: (A) 56 mm (B) 62 mm (C) 75 mm (D) 82 mm