5–39. The solid steel shaft DF has a diameter of 25 mm and
is supported by smooth bearings at D and E. It is coupled to
a motor at F, which delivers 12 kW of power to the shaft
while it is turning at 50 rev>s. If gears A, B, and C remove
3 kW, 4 kW, and 5 kW respectively, determine the maximum
shear stress developed in the shaft within regions CF and
BC. The shaft is free to turn in its support bearings D and E.