Torsion of Shafts MCQ – Objective Questions with Answers
Mechanical Engineering › Strength of Materials | Free practice MCQs with detailed explanations
Last Updated: June 2026
📌 About this MCQ Set
Torsion is the twisting of a shaft due to an applied torque. The torsion equation relates torque, shear stress, angle of twist and the polar moment of inertia.
These MCQs cover the torsion equation, polar moment of inertia, power transmission and stress distribution.
8 questions • every answer comes with a worked explanation. Click Show Answer to check yourself.
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Torsion of Shafts MCQs
Q1. The torsion equation for a circular shaft is:
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Answer: A. T/J = τ/r = Gθ/L
Torsion equation: T/J = τ/r = Gθ/L.
Q2. The polar moment of inertia (J) of a solid circular shaft of diameter d is:
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Answer: B. πd⁴/32
J = πd⁴/32 for a solid circular section.
Q3. In a shaft under torsion, shear stress is maximum at:
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Answer: B. The outer surface
Shear stress varies linearly with radius and is maximum at the outer surface.
Q4. The shear stress at the axis (centre) of a shaft under torsion is:
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Answer: B. Zero
At r = 0 the shear stress is zero.
Q5. Polar modulus (Zp) is defined as:
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Answer: B. J / r
Polar modulus Zp = J / r; it measures torsional strength.
Q6. Torsional rigidity of a shaft is given by:
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Answer: A. G·J
Torsional rigidity = G·J; it resists angular twist.
Q7. The power transmitted by a shaft rotating at N rpm under torque T is:
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Answer: A. 2πNT/60
P = 2πNT/60 watts, with T in N·m and N in rpm.
Q8. For a hollow shaft of outer diameter D and inner diameter d, J equals:
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Answer: A. π(D⁴−d⁴)/32
J = π(D⁴ − d⁴)/32 for a hollow circular section.
Frequently Asked Questions
What is the torsion equation?
T/J = τ/r = Gθ/L, relating torque, polar moment of inertia, shear stress, radius, modulus of rigidity, angle of twist and length.
Where is shear stress maximum in a shaft?
At the outer surface (maximum radius); it is zero at the axis and varies linearly in between.
Why are hollow shafts preferred for transmitting torque?
Hollow shafts give a higher strength-to-weight ratio because material near the axis carries little stress, so it can be removed with small loss of strength.