Strength of Materials

JKSSB Junior Engineer (Mechanical) · Technical Subjects (Mechanical) · 29 practice questions with answers and explanations: 8 Easy, 20 Medium, 1 Hard.

Sample questions

Sample Easy question 1

Poisson's ratio is the ratio of:

  1. Volume change to original volume
  2. Lateral strain to longitudinal strain
  3. Shear stress to shear strain
  4. Longitudinal strain to lateral strain
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Answer: B. It is taken as a positive number.

Sample Easy question 2

The effective length of a column with one end fixed and the other free is:

  1. L
  2. 0.7 L
  3. L / 2
  4. 2L
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Answer: D. Such a column is the weakest of the standard end conditions.

Sample Easy question 3

The factor of safety is the ratio of:

  1. Yield stress to proportional limit
  2. Ultimate stress to working (allowable) stress
  3. Load to area
  4. Working stress to ultimate stress
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Answer: B. A higher factor gives a larger margin.

Sample Medium question 4

The endurance limit is the stress:

  1. Below which a material can withstand an infinite number of cycles
  2. At which creep begins
  3. Equal to ultimate tensile strength
  4. At which the material yields
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Answer: A. It is the key quantity in fatigue design.

Sample Medium question 5

Young's modulus of mild steel is about:

  1. 2,000 GPa
  2. 200 GPa
  3. 2 GPa
  4. 20 GPa
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Answer: B. Steel is about 2 × 10⁵ MPa.

Sample Medium question 6

The relation between Young's modulus E, modulus of rigidity G and Poisson's ratio ν is:

  1. E = G / (1 + ν)
  2. E = 3G(1 + ν)
  3. E = G(1 − 2ν)
  4. E = 2G(1 + ν)
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Answer: D. For steel, with ν ≈ 0.3, G is about 0.38 E.

Sample Hard question 7

The relation between Young's modulus E, bulk modulus K and Poisson's ratio ν is:

  1. E = 3K(1 − 2ν)
  2. E = K / (1 − 2ν)
  3. E = K(1 + 2ν)
  4. E = 2K(1 + ν)
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Answer: A. As ν approaches 0.5, K becomes very large, which describes an almost incompressible material.

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