This set of Mechanical Behaviour Multiple Choice Questions & Answers (MCQs) focuses on “Elastic Deformation”.
1. If the material recovers the original dimensions, when an external load is removed, this deformation is known as ______ deformation.
a) plastic
b) permanent
c) elastic
d) irreversible
View Answer
Explanation: If the applied load is small, the material deforms temporarily. The material recovers its original dimensions on the removal of a load in such case. This type of deformation is known as elastic deformation.
2. The negative ratio between the lateral strain and the direct tensile strain is known as ______
a) True strain
b) Engineering strain
c) Poisson’s ratio
d) Elastic modulus
View Answer
Explanation: The negative ratio between the lateral strain and the direct tensile strain is called Poisson’s ratio. Its range is in between 0.25 and 0.50.
3. What is the relation between shear modulus (G) and elastic modulus (E)?
a) G = E
b) G = 0.35 E
c) G = 0.50 E
d) G = 0.75 E
View Answer
Explanation: G and E are related as G = E/2 (1 + v). Here v is Poisson’s ratio, which varies between 0.25 and 0.50. On approximation of this relation, we get G = 0.35 E.
4. What is the expression for bulk modulus?
a) E/2(1 + v)
b) E/3(1 – 2v)
c) E/ (1 – 2v)
d) E/3(1 + v)
View Answer
Explanation: Bulk modulus is reciprocal of compressibility of material. It is expressed as K = E/3(1 – 2v). Here E is elastic modulus and v is Poisson’s ratio.
5. Compressibility is reciprocal of _____
a) Shear modulus
b) Elastic modulus
c) Bulk modulus
d) Poisson’s ratio
View Answer
Explanation: Bulk modulus (K) is a reciprocal of compressibility. Compressibility is represented by β. Hence K = 1/ β.
6. _____ is an anisotropic property of a crystal.
a) Elastic modulus
b) Density
c) Poisson’s ratio
d) Damping
View Answer
Explanation: Elastic modulus is an anisotropic property of a crystal. Its value varies with crystal directions. While Poisson’s ratio, damping and density are isotropic properties.
7. What is the value of elastic modulus of graphite in the direction parallel to sheets?
a) 8 GPa
b) 400 GPa
c) 580 GPa
d) 950 GPa
View Answer
Explanation: Elastic modulus of graphite is observed differently in different directions. It is 950 GPa in direction parallel to sheets. While the average value in all directions is 8 GPa.
8. The restoring force depends on _____
a) Interatomic bond strength
b) Melting point
c) Crystallization
d) Thermal conductivity
View Answer
Explanation: To produce a given strain, a larger load is required for a higher strain. The restoring force depends on strength of interatomic bonds. As strength increases, restoring attractive forces also increase.
9. What is the reason for elastic deformation?
a) Dislocations intersection
b) Twinning
c) Slip
d) Displacement of atoms to a fraction interatomic distance
View Answer
Explanation: On application of small amount of load, atoms may displace to a fraction of interatomic distance. It is known as elastic deformation. On removal of load, atoms come to their equilibrium positions.
10. Elastic modulus can’t be changed by ______
a) alloying
b) cold working
c) heat treatment
d) by increasing section thickness
View Answer
Explanation: Heat treatments are unable to change the elastic modulus significantly. It is because it only changes the slightly atomic spacing. Drastic change in alloy composition can increase elastic modulus.
11. By altering composition or heat treatment, elastic modulus can be increased to very high orders.
a) True
b) False
View Answer
Explanation: Alternation in a composition can only change elastic modulus to a small level. Heat treatment is unable to improve elastic modulus of material significantly. They both can increase the elastic modulus only less than 10%.
12. For higher intermolecular bond strength, value of elastic modulus is higher.
a) True
b) False
View Answer
Explanation: Modulus of elasticity is a measure of the stiffness of a material. For higher intermolecular bond strength, stiffness increases. Value of elastic modulus is also observed higher.
Sanfoundry Global Education & Learning Series – Mechanical Behaviour & Testing of Materials.
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