A shaft of solid circular cross section consisting of two segments is shown in the first part of the figure. The left-hand segment has diameter 80 mm and length 1.2 m; the right-hand segment has diameter 60 mm and length 0.9 m.
Shown in the second part of the figure is a hollow shaft made of the same material and having the same length. The thickness t of the hollow shaft is d/10, where d is the outer diameter. Both shafts are subjected to the same torque.
If the hollow shaft is to have the same torsional stiffness as the solid shaft, what should be its outer diameter d?

Transcribed Image Text:

80 mm 60 mm 1.2 -0.9 m 10 2.1 m