# Strength of Materials Questions and Answers – Hooke’s Law

This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Hooke’s Law”.

1. The law which states that within elastic limits strain produced is proportional to the stress producing it is known as _____________
a) Bernoulli’s law
b) Hooke’s law
c) Stress law
d) Poisson’s law

Explanation: Hooke’s law states that strain is directly proportional to strain produced by the stress when a material is loaded within the elastic limit.

2. For an isotropic, homogeneous and elastic material obeying Hooke’s law, the number of independent elastic constants is ____________
a) 2
b) 3
c) 9
d) 1

Explanation: There are 3 constants Young’s modulus, Shear modulus and Bulk modulus.

3. What is the factor of safety?
a) The ratio of stress to strain
b) The raio of permissible stress to the ultimate stress
c) The ratio of ultimate stress to the permissible stress
d) The ratio of longitudinal strain to stress

Explanation: Factor of safety is the ratio of ultimate stress to the permissible stress.

4. What is Hooke’s law for the 1-D system?
a) The relation between normal stress and the corresponding strain
b) The relation between shear stress and the corresponding strain
c) The relation between lateral strain and the corresponding stress
d) None of the mentioned

Explanation: For the 1-D system, the stress will be only in one direction. Lateral stress is for an area while normal stress is of a length.

5. Limit of proportionality depends upon ____________
a) Area of cross-section
c) Type of material
d) All of the mentioned

Explanation: The proportionality limit is proportional to the area of cross-section. The material type and loading type will have no influence on the proportionality limit.

6. The stress at which extension of a material takes place more quickly as compared to the increase in load is called ____________
a) Elastic point
b) Plastic point
c) Breaking point
d) Yielding point

Explanation: On the stress strain curve, on the elastic point the stress of a material takes place more quickly.

7. Which of these is a non-hoookean material?
a) Steel
b) Rubber
c) Aluminium
d) Copper

Explanation: Rubber is generally regarded as a “non-hookean” material because its elasticity is stress dependent and sensitive to temperature and loading rate.

8. Where in the stress-strain curve, the hooke’s law is valid?
a) Strain hardening region
b) Necking region
c) Elastic range
d) Valid everywhere

Explanation: The hooke’s law itself states that it is valid only up to the elastic range of the material I.e. only to that limit where the material is behaving elastic.

9. Highest value of stress for which Hooke’s law is applicable for a given material is called ____________
a) Stress limit
b) Strain limit
c) Proportional limit
d) Significant limit

Explanation: The hooke’s law is valid only when the stress is proportional to the strain, that is only in the proportionality limit.