고체역학 (Beer) — Torsion: Problem 3.152

3.152 A torque of magnitude \( T = 120 \text{ N}\cdot\text{m} \) is applied to shaft \( AB \) of the gear train shown. Knowing that the allowable shearing stress is \( 75 \text{ MPa} \) in each of the three solid shafts, determine the required diameter of (a) shaft \( AB \), (b) shaft \( CD \), (c) shaft \( EF \).