STRENGTH OF MATERIAL MCQ SET 5
Q1. The relation between Youngโs modulus (E), shear modulus (G), and Poissonโs ratio (ฮฝ) is:
A) E = 2G(1 + ฮฝ)
B) E = G(1 + 2ฮฝ)
C) E = 3G(1 + ฮฝ)
D) E = G/ฮฝ
Answer: A) E = 2G(1 + ฮฝ)
Explanation: This formula relates elasticity constants of isotropic materials.
Q2. The total angle of twist (ฮธ) in a shaft is directly proportional to:
A) Torque
B) Length of shaft
C) Inversely proportional to G and J
D) All of the above
Answer: D) All of the above
Explanation: ฮธ = TL / GJ โ proportional to T and L, inversely to G and J.
Q3. The section modulus of a beam is defined as:
A) I/y
B) y/I
C) M/ฯ
D) Both A and C
Answer: D) Both A and C
Explanation: Section modulus Z = I/y = M/ฯ, measures bending strength of section.
Q4. When a material is subjected to shear stress, the strain produced is:
A) Longitudinal
B) Lateral
C) Angular
D) Volumetric
Answer: C) Angular
Explanation: Shear stress produces angular deformation.
Q5. The maximum shear stress in a circular shaft is:
A) 16T/ฯDยณ
B) 32T/ฯDยณ
C) 64T/ฯDยณ
D) 8T/ฯDยณ
Answer: B) 32T/ฯDยณ
Explanation: For solid circular shafts, ฯmax = 16T/ฯrยณ = 32T/ฯDยณ.
Q6. The point of contraflexure occurs where:
A) Shear force is maximum
B) Bending moment is zero
C) Bending moment changes sign
D) Shear stress is zero
Answer: C) Bending moment changes sign
Explanation: Contraflexure means โchange of curvatureโ in bending moment diagram.
Q7. A simply supported beam with a UDL has maximum deflection at:
A) Quarter span
B) Mid-span
C) Support
D) One-third span
Answer: B) Mid-span
Explanation: The center experiences maximum deflection for UDL beams.
Q8. Moment of inertia of a circular section about its diameter is:
A) ฯdโด/32
B) ฯdโด/64
C) ฯdโด/16
D) ฯdโด/8
Answer: B) ฯdโด/64
Explanation: I = ฯdโด / 64 for solid circular sections.
Q9. When a body is under torsion, which stress is developed?
A) Normal stress
B) Shear stress
C) Compressive stress
D) Tensile stress
Answer: B) Shear stress
Explanation: Torsion always produces shear stress over the cross-section.
Q10. The maximum bending stress in a beam is directly proportional to:
A) Bending moment
B) Section modulus
C) Moment of inertia
D) Radius of gyration
Answer: A) Bending moment
Explanation: From ฯ = M/Z, stress increases linearly with bending moment.
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