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1. The property of a body to regain its original shape and size after removal of the deforming force is called
A. Elasticity
B. Plasticity
C. Ductility
D. Malleability
Answer: A. Elasticity
Explanation: Elasticity is the property by virtue of which a body regains its original shape and size when the deforming force is removed.
2. Stress is defined as
A. Restoring force per unit area
B. Change in dimension per original dimension
C. Force per unit volume
D. Energy stored per unit area
Answer: A. Restoring force per unit area
Explanation: Stress is defined as the internal restoring force acting per unit area of a deformed body.
3. The SI unit of stress is
A. N/m² (Pascal)
B. N/m
C. Joule
D. No unit
Answer: A. N/m² (Pascal)
Explanation: Since stress is force per unit area, its SI unit is N/m², also called Pascal (Pa).
4. Strain is a
A. Dimensionless quantity
B. Vector quantity
C. Quantity with unit N/m²
D. Quantity with unit N/m
Answer: A. Dimensionless quantity
Explanation: Strain is the ratio of change in dimension to original dimension, so it has no units and no dimensions.
5. Hooke's law states that, within elastic limit
A. Stress is directly proportional to strain
B. Stress is inversely proportional to strain
C. Stress equals strain
D. Stress is proportional to the square of strain
Answer: A. Stress is directly proportional to strain
Explanation: Hooke's law states that within the elastic limit, stress is proportional to strain, i.e., stress = k × strain, where k is the modulus of elasticity.
6. The ratio of longitudinal stress to longitudinal strain is called
A. Young's modulus
B. Bulk modulus
C. Shear modulus
D. Poisson's ratio
Answer: A. Young's modulus
Explanation: Young's modulus (Y) is defined as the ratio of longitudinal stress to longitudinal strain.
7. The ratio of hydraulic stress to volumetric strain is called
A. Bulk modulus
B. Young's modulus
C. Shear modulus
D. Compressibility
Answer: A. Bulk modulus
Explanation: Bulk modulus (K) is defined as the ratio of hydraulic stress to the corresponding volumetric strain.
8. The reciprocal of bulk modulus is called
A. Compressibility
B. Rigidity modulus
C. Elastic limit
D. Poisson's ratio
Answer: A. Compressibility
Explanation: Compressibility is defined as the reciprocal of the bulk modulus, i.e., Compressibility = 1/K.
9. Shear modulus relates
A. Shearing stress to shearing strain
B. Longitudinal stress to longitudinal strain
C. Hydraulic stress to volumetric strain
D. Lateral strain to longitudinal strain
Answer: A. Shearing stress to shearing strain
Explanation: Shear modulus (rigidity modulus) is defined as the ratio of shearing stress to the corresponding shearing strain.
10. Poisson's ratio is defined as
A. Ratio of lateral strain to longitudinal strain
B. Ratio of longitudinal strain to lateral strain
C. Ratio of stress to strain
D. Ratio of volume strain to longitudinal strain
Answer: A. Ratio of lateral strain to longitudinal strain
Explanation: Poisson's ratio is the ratio of lateral strain to the longitudinal strain produced in a stretched wire, and has no units.
11. On the stress-strain curve, the point up to which stress is proportional to strain is called the
A. Proportional limit
B. Fracture point
C. Yield point
D. Ultimate point
Answer: A. Proportional limit
Explanation: Up to the proportional limit, the stress-strain curve is a straight line and Hooke's law is obeyed.
12. The point beyond which the material undergoes plastic deformation is called
A. Yield point
B. Proportional limit
C. Fracture point
D. Neutral point
Answer: A. Yield point
Explanation: Beyond the yield point, even a small increase in stress produces a large strain, and the deformation becomes plastic.
13. Materials that can be drawn into thin wires are called
A. Ductile
B. Brittle
C. Elastomers
D. Rigid
Answer: A. Ductile
Explanation: Materials like copper and aluminium that can be drawn into thin wires are called ductile materials.
14. Materials that break as soon as the stress exceeds the elastic limit, with little plastic deformation, are called
A. Brittle
B. Ductile
C. Malleable
D. Elastic
Answer: A. Brittle
Explanation: Brittle materials such as glass and cast iron break almost as soon as the elastic limit is exceeded.
15. Substances like rubber, which can be stretched to a large extent, are called
A. Elastomers
B. Ductile substances
C. Brittle substances
D. Isotropic substances
Answer: A. Elastomers
Explanation: Elastomers, such as rubber, can be stretched considerably and do not obey Hooke's law over most of the range.
16. Among steel and rubber, which has a higher Young's modulus for a given strain?
A. Steel
B. Rubber
C. Both are equal
D. Cannot be determined
Answer: A. Steel
Explanation: Steel is more elastic in the sense of having a much higher Young's modulus than rubber for the same strain, hence steel is called more elastic.
17. A wire is said to obey Hooke's law only
A. Within its elastic limit
B. At the yield point
C. Beyond the fracture point
D. At all values of strain
Answer: A. Within its elastic limit
Explanation: Hooke's law, stress ∝ strain, holds true only within the elastic limit of the material.
18. The energy stored per unit volume of a stretched wire is called
A. Elastic potential energy density
B. Kinetic energy density
C. Strain energy per unit mass
D. Thermal energy density
Answer: A. Elastic potential energy density
Explanation: The work done in stretching a wire is stored as elastic potential energy, and per unit volume it equals ½ × stress × strain.
19. Why are bridge girders given an I-shaped cross section?
A. To reduce material used while maintaining strength against bending
B. To make them lighter but weaker
C. To increase their weight for stability
D. To make manufacturing cheaper without strength consideration
Answer: A. To reduce material used while maintaining strength against bending
Explanation: The I-shaped cross-section provides a large depression resistance (bending strength) while using less material, since bulk of the material is kept away from the neutral axis.
20. For a given material, which modulus of elasticity is generally the largest?
A. Bulk modulus for solids is usually largest
B. Shear modulus is always largest
C. Young's modulus is always the smallest
D. All moduli are always equal
Answer: A. Bulk modulus for solids is usually largest
Explanation: For most solid materials, the bulk modulus (K) is generally larger than Young's modulus (Y) and shear modulus (G), reflecting greater resistance to volume change than shape change.
21. If the length of a wire is doubled and its radius is halved, keeping the material same, how does its Young's modulus change?
A. It remains the same
B. It doubles
C. It becomes half
D. It becomes four times
Answer: A. It remains the same
Explanation: Young's modulus is a property of the material only and does not depend on the dimensions (length or radius) of the wire.
22. Which of the following best explains why springs are made of steel and not copper?
A. Steel has a higher elastic limit than copper
B. Copper is more expensive than steel
C. Steel is lighter than copper
D. Copper cannot be shaped into springs
Answer: A. Steel has a higher elastic limit than copper
Explanation: Steel has a greater elastic limit and Young's modulus than copper, so it can be deformed more and still return to its original shape, making it suitable for springs.
23. Elastic hysteresis is observed most prominently in
A. Elastomers such as rubber and vulcanised rubber
B. Perfectly rigid bodies
C. Ideal gases
D. Metals like steel only
Answer: A. Elastomers such as rubber and vulcanised rubber
Explanation: In elastic hysteresis, the strain-curve for increasing and decreasing load does not retrace itself, and the area of the loop represents energy dissipated as heat, a property prominent in vulcanised rubber.
24. A quantity that measures how much a substance resists being compressed uniformly is
A. Bulk modulus
B. Young's modulus
C. Shear modulus
D. Poisson's ratio
Answer: A. Bulk modulus
Explanation: Bulk modulus measures a substance's resistance to uniform compression under hydraulic stress applied from all sides.
25. Which of the following materials has zero shear modulus?
A. Fluids (liquids and gases)
B. Steel
C. Copper
D. Glass
Answer: A. Fluids (liquids and gases)
Explanation: Fluids cannot sustain a shearing stress since they flow under it, so their shear modulus is zero; only solids possess a measurable shear modulus.
26. In a stress-strain graph for a typical metal wire, the region beyond the yield point but before fracture is called the
A. Plastic region
B. Elastic region
C. Fracture region only
D. Proportional region
Answer: A. Plastic region
Explanation: Beyond the yield point, the material undergoes plastic deformation and does not return to its original shape when the load is removed.
27. The pillars used in buildings are usually made thicker at the ends because
A. Stress concentration is greater near the ends, so they need to bear more load
B. It reduces the total material used
C. It makes the pillar lighter
D. It is only for aesthetic purposes
Answer: A. Stress concentration is greater near the ends, so they need to bear more load
Explanation: Pillars are designed with tapering that keeps them thick where the load and resulting stress is greatest, ensuring the structure can withstand compressive stress safely.
28. What happens to the strain energy of a wire if the stretching force is doubled (within elastic limit)?
A. It becomes four times
B. It doubles
C. It remains the same
D. It becomes half
Answer: A. It becomes four times
Explanation: Since strain energy is proportional to the square of the stress (or force) within the elastic limit, doubling the force makes the stored energy four times as much.
29. Which of these correctly relates the three elastic moduli (Y, K, G) and Poisson's ratio (σ) for an isotropic material?
A. They are interrelated, so knowing any two determines the others
B. They are completely independent of one another
C. Only Y and K are related; G is independent
D. Poisson's ratio has no relation to the elastic moduli
Answer: A. They are interrelated, so knowing any two determines the others
Explanation: For an isotropic elastic solid, Young's modulus, bulk modulus, shear modulus, and Poisson's ratio are related through known formulas, so only two independent elastic constants are needed to describe the material.
30. A metal wire behaves elastically as long as
A. The applied stress does not exceed the elastic limit
B. The applied stress is beyond the fracture point
C. The strain is greater than one
D. The temperature is constant
Answer: A. The applied stress does not exceed the elastic limit
Explanation: A material behaves elastically and returns to its original shape only if the applied stress stays within its elastic limit; beyond that, permanent deformation occurs.
This page contains a chapter-wise objective practice set. Try the questions without checking the answer first, then use the explanation to understand the point you missed. The current page contains 30 questions, so you can practise in smaller sets when you are revising.
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