Which of the following terms represents the torque that produces a twist of one radian in a shaft of unit length?
Try it first: pick an option, then read the explanation.
Correct answer: B. Torsional rigidity
Asked in SSC JE 23/03/2021 (Evening)
Detailed Explanation
Rearranging the torsion equation gives GJ = TL/θ.
Why “Torsional rigidity” Is Correct
Setting L = 1 and θ = 1 rad gives T = GJ, the torsional rigidity.
Why the Other Options Are Wrong
- A. Flexural rigidity: Flexural rigidity EI relates bending moment to curvature.
- C. Moment of resistance: Moment of resistance is the internal resisting bending moment of a section.
- D. Torsional stress: Torsional stress is the shear stress τ, not a torque.
Key Point
Torsional rigidity GJ: torque for unit twist per unit length.
Key Concepts for Students
- Stiffer shafts have larger G or J.
- θ = TL/GJ.
- Hollow shafts give larger J per unit weight.
Practice more: this is question 4 in Torsion MCQs – Part 1. Try the whole set and check every answer instantly.