MCQ Physics Chapter–9: Mechanical Properties of Solids, HS 1st year

 

Introduction to Mechanical Properties of Solids

1. What is the property of a material that allows it to regain its original shape after deformation?

   • A) Plasticity
   • B) Elasticity
   • C) Rigidity
   • D) Toughness
   • Answer: B

2. A material that gets permanently deformed after applying force is called:

   • A) Elastic
   • B) Plastic
   • C) Brittle
   • D) Ductile
   • Answer: B

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Stress and Strain

3. Stress is defined as:

   • A) Force per unit area
   • B) Force times area
   • C) Force per unit volume
   • D) Force times volume
   • Answer: A

4. What is the SI unit of stress?

   • A) Pascal (Pa)
   • B) Newton (N)
   • C) Joule (J)
   • D) Watt (W)
   • Answer: A

5. Strain is:

   • A) Dimensionless
   • B) Measured in meters
   • C) Measured in pascals
   • D) Measured in kilograms
   • Answer: A

6. Longitudinal strain is calculated as:

   • A) $\Delta L / L$
   • B) $F / A$
   • C) $V / \Delta V$
   • D) $\Delta A / A$
   • Answer: A

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Types of Stress and Strain

7. Tensile stress results in:

   • A) Compression
   • B) Elongation
   • C) Shear deformation
   • D) Volume reduction
   • Answer: B

8. Hydraulic stress leads to:

   • A) Change in shape only
   • B) Change in volume only
   • C) Change in both shape and volume
   • D) No change
   • Answer: B

9. Shearing strain is expressed as:

   • A) $\Delta L / L$
   • B) $\tan \theta$
   • C) $F / A$
   • D) $p / B$
   • Answer: B

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Hooke's Law

10. Hooke’s Law states that stress is proportional to:

    • A) Force
    • B) Strain
    • C) Area
    • D) Volume
    • Answer: B

11. The constant of proportionality in Hooke’s Law is called:

    • A) Stress
    • B) Modulus of elasticity
    • C) Yield strength
    • D) Strain limit
    • Answer: B

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Elastic Moduli

12. Young’s modulus is the ratio of:

    • A) Shearing stress to shearing strain
    • B) Tensile stress to tensile strain
    • C) Hydraulic stress to hydraulic strain
    • D) Bulk stress to bulk strain
    • Answer: B

13. Bulk modulus is relevant for:

    • A) Solids only
    • B) Liquids only
    • C) Solids, liquids, and gases
    • D) Gases only
    • Answer: C

14. The shear modulus is also known as:

    • A) Modulus of elasticity
    • B) Modulus of rigidity
    • C) Poisson’s ratio
    • D) Bulk modulus
    • Answer: B

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Stress-Strain Curve

15. The elastic limit on the stress-strain curve is represented by:

    • A) Point A
    • B) Point B
    • C) Point D
    • D) Point E
    • Answer: B

16. If a material fractures without much elongation, it is termed as:

    • A) Ductile
    • B) Brittle
    • C) Elastic
    • D) Plastic
    • Answer: B

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Applications of Elastic Behavior

17. Steel is preferred for construction because:

    • A) It is cheaper than other materials
    • B) It has a higher Young’s modulus
    • C) It is lightweight
    • D) It has a lower bulk modulus
    • Answer: B

18. The I-shaped cross-section of beams reduces:

    • A) Cost
    • B) Weight and bending
    • C) Stress only
    • D) Material usage
    • Answer: B

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General Properties

19. Poisson’s ratio is:

    • A) The ratio of stress to strain
    • B) The ratio of lateral strain to longitudinal strain
    • C) The ratio of longitudinal strain to lateral strain
    • D) The ratio of stress to lateral strain
    • Answer: B

20. Elastic potential energy per unit volume is given by:

• A) $\frac{1}{2} \sigma \epsilon$
• B) $\sigma / \epsilon$
• C) $\sigma \times \epsilon$
• D) $2 \sigma \epsilon$
• Answer: A

21. If the length of a wire increases from 1.0 m to 1.01 m under a load, the strain is:

    • A) 0.01
    • B) 0.001
    • C) 0.1
    • D) 10
    • Answer: B

22. The unit of bulk modulus is the same as:

    • A) Strain
    • B) Stress
    • C) Displacement
    • D) Velocity
    • Answer: B

23. For most materials, the shear modulus $G$ is approximately:

    • A) Equal to the Young’s modulus $Y$
    • B) Double the Young’s modulus
    • C) One-third of the Young’s modulus
    • D) Half of the Young’s modulus
    • Answer: C

24. The bulk modulus of a substance measures its:

    • A) Rigidity
    • B) Compressibility
    • C) Tensile strength
    • D) Elasticity
    • Answer: B

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Stress-Strain Behavior

25. What does the slope of the linear portion of a stress-strain curve represent?

    • A) Yield strength
    • B) Ultimate tensile strength
    • C) Modulus of elasticity
    • D) Fracture point
    • Answer: C

26. Beyond the yield point, a material undergoes:

    • A) Elastic deformation
    • B) Plastic deformation
    • C) Brittle fracture
    • D) Shear strain
    • Answer: B

27. If a material returns to its original dimensions after the removal of force, it is in the:

    • A) Plastic region
    • B) Elastic region
    • C) Fracture region
    • D) Strain-hardening region
    • Answer: B

28. The area under the stress-strain curve represents:

    • A) Stress
    • B) Strain
    • C) Energy stored per unit volume
    • D) Modulus of elasticity
    • Answer: C

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Poisson's Ratio and Related Concepts

29. For a material, Poisson’s ratio is typically:

    • A) Greater than 1
    • B) Less than 1
    • C) Zero
    • D) Infinite
    • Answer: B

30. Poisson's ratio for most steels is approximately:

    • A) 0.5
    • B) 0.3
    • C) 0.7
    • D) 0.9
    • Answer: B

31. If the lateral contraction in a stretched wire is $-\Delta d$ and the elongation is $\Delta L$, the Poisson's ratio is:

    • A) $\Delta d / \Delta L$
    • B) $-\Delta d / \Delta L$
    • C) $\Delta L / \Delta d$
    • D) $\Delta L / (\Delta d \cdot d)$
    • Answer: B

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Practical Applications

32. A material with a large Young’s modulus:

    • A) Stretches significantly under small force
    • B) Requires a large force to produce small elongation
    • C) Compresses easily
    • D) Deforms plastically under load
    • Answer: B

33. Why are steel ropes used in cranes?

    • A) They are lightweight
    • B) They have a high yield strength
    • C) They have low cost
    • D) They are brittle
    • Answer: B

34. The cross-section of most load-bearing beams is:

    • A) Circular
    • B) Rectangular
    • C) I-shaped
    • D) Square
    • Answer: C

35. The pyramidal shape of a heap of sand is due to:

    • A) Shear stress
    • B) Hydraulic stress
    • C) Tensile strength
    • D) Elastic modulus
    • Answer: A

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Elastic Potential Energy

36. Elastic potential energy in a stretched wire depends on:

    • A) Length only
    • B) Cross-sectional area only
    • C) Both stress and strain
    • D) Pressure only
    • Answer: C

37. The elastic potential energy per unit volume is:

    • A) Directly proportional to strain
    • B) Inversely proportional to stress
    • C) Proportional to the product of stress and strain
    • D) Independent of strain
    • Answer: C

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Miscellaneous

38. What happens to a material subjected to stress beyond its elastic limit?

    • A) It fractures immediately
    • B) It undergoes plastic deformation
    • C) It remains elastic
    • D) It shows no change
    • Answer: B

39. A brittle material has:

    • A) A large plastic region
    • B) A small plastic region
    • C) High ductility
    • D) High strain without failure
    • Answer: B

40. The material of a stretched wire that can store the most elastic potential energy is:

    • A) The most elastic material
    • B) The least elastic material
    • C) A material with low Young's modulus
    • D) A material with high stress capacity
    • Answer: A