Stress and Strain
JKSSB Junior Engineer (Civil) · Mechanics and Structural Analysis · 16 practice questions with answers and explanations: 5 Easy, 9 Medium, 2 Hard.
Sample questions
Sample Easy question 1
Young's modulus is the ratio of:
- Stress to strain in the elastic range
- Shear stress to shear strain
- Load to area
- Strain to stress
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Answer: A. E = σ ÷ ε within the proportional limit.
Sample Easy question 2
The Poisson's ratio of steel is about:
- 3
- 0.3
- 0.03
- 1.3
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Answer: B. Most metals have Poisson's ratio between 0.25 and 0.35.
Sample Easy question 3
The relation between the elastic constants E, G and μ is:
- E = 2G(1 + μ)
- E = G(1 − 2μ)
- E = 3G(1 + μ)
- E = G ÷ (1 + μ)
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Answer: A. E = 2G(1 + μ) and E = 3K(1 − 2μ) link the three moduli.
Sample Medium question 4
An element has principal stresses of 80 and 20 N/mm² with no shear. The maximum shear stress is:
- 50 N/mm²
- 30 N/mm²
- 60 N/mm²
- 100 N/mm²
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Answer: B. τmax = (σ₁ − σ₂) ÷ 2 = 30 N/mm².
Sample Medium question 5
A bar has an axial strain of 0.001 and a Poisson's ratio of 0.3. The volumetric strain is:
- 0.0004
- 0.0016
- 0.003
- 0.001
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Answer: A. εv = ε (1 − 2μ) = 0.001 × 0.4 = 0.0004.
Sample Medium question 6
A material with E = 200 GPa and μ = 0.3 has a bulk modulus of:
- 76.9 GPa
- 240 GPa
- 200 GPa
- 166.7 GPa
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Answer: D. K = E ÷ [3 (1 − 2μ)] = 200 ÷ 1.2 = 166.7 GPa.
Sample Hard question 7
A steel bar of 500 mm² area and 2 m length carries a tensile load of 50 kN, with E = 200 GPa. The elongation is:
- 1 mm
- 0.1 mm
- 2 mm
- 10 mm
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Answer: A. δ = P L ÷ (A E) = 50,000 × 2,000 ÷ (500 × 200,000) = 1 mm.
Sample Hard question 8
A steel bar (α = 12 × 10⁻⁶ per °C, E = 200 GPa) is held fixed at both ends and heated by 40°C. The thermal stress is:
- 48 N/mm²
- 9.6 N/mm²
- 96 N/mm²
- 192 N/mm²
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Answer: C. σ = α × ΔT × E = 12 × 10⁻⁶ × 40 × 200,000 = 96 N/mm².