The stepped solid steel shaft ABC is attached to rigid supports at each end. Determine the diameter of segment BC for which the maximum shear stress in both segments will be equal when the torque T is...

The stepped solid steel shaft
ABC
is attached to rigid supports at each end. Determine the diameter of segment
BC
for which the maximum shear stress in both segments will be equal when the torque
T
is applied at
B. Note that the lengths of both segments are given and the diameter of segment
AB
is 60 mm.