고체역학 (Beer) — Torsion: Problem 3.77

3.77 The two solid shafts and gears shown are used to transmit 16 hp from the motor at A operating at a speed of 1260 rpm to a machine tool at D. Knowing that the maximum allowable shearing stress is 8 ksi, determine the required diameter of (a) shaft AB, (b) shaft CD.