Strength of Material MCQ Set 7
STRENGTH OF MATERIAL MCQ SET 7
Q1. The torsional equation is:
A) T/J = τ/R = Gθ/L
B) T/J = σ/y
C) M/I = f/y
D) τ = Gθ
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Answer: A) T/J = τ/R = Gθ/L
Explanation: This is the fundamental torsion equation used in circular shafts.
Q2. The maximum shear stress in a solid circular shaft occurs at:
A) Axis of shaft
B) Outer surface
C) Middle
D) Neutral layer
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Answer: B) Outer surface
Explanation: Shear stress increases from zero at the center to maximum at the outer surface.
Q3. The polar moment of inertia for a solid circular shaft of diameter D is:
A) πD³/16
B) πD⁴/32
C) πD⁴/64
D) πD⁴/8
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Answer: B) πD⁴/32
Explanation: Polar moment of inertia J = πD⁴/32 for a solid circular cross-section.
Q4. In torsion, the angle of twist is directly proportional to:
A) Length of shaft
B) Modulus of rigidity
C) Polar moment of inertia
D) Diameter of shaft
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Answer: A) Length of shaft
Explanation: θ = (TL)/(JG), so longer shafts twist more under same torque.
Q5. The strain energy stored in a shaft under torsion is called:
A) Resilience
B) Torsional energy
C) Shear strain energy
D) Twisting energy
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Answer: C) Shear strain energy
Explanation: It is the energy stored due to shear stress in torsion.
Q6. The term “spring index” is defined as:
A) Mean coil diameter / Wire diameter
B) Wire diameter / Mean coil diameter
C) Number of turns / Pitch
D) Pitch / Number of turns
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Answer: A) Mean coil diameter / Wire diameter
Explanation: Spring index (C) = D/d, it affects the stiffness and stress in springs.
Q7. The stiffness of a spring is the ratio of:
A) Load to deflection
B) Deflection to load
C) Load to number of turns
D) Wire diameter to mean coil diameter
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Answer: A) Load to deflection
Explanation: Stiffness (k) = W/δ, representing the resistance to deformation.
Q8. The modulus of rigidity (G) for steel is approximately:
A) 80 GPa
B) 200 GPa
C) 100 GPa
D) 160 GPa
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Answer: A) 80 GPa
Explanation: For steel, G ≈ 80 × 10⁹ N/m².
Q9. The deflection of a cantilever beam with a point load at free end is given by:
A) WL³/3EI
B) WL³/8EI
C) WL³/48EI
D) WL³/2EI
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Answer: A) WL³/3EI
Explanation: Formula for deflection δ = WL³ / (3EI).
Q10. The deflection in a simply supported beam under central load is:
A) WL³/8EI
B) WL³/48EI
C) WL³/16EI
D) WL³/12EI
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Answer: B) WL³/48EI
Explanation: δ = WL³ / (48EI) for simply supported beam under central load.