# Strength of Materials Questions and Answers – Strain

This set of Strength of Materials Multiple Choice Questions & Answers (MCQs) focuses on “Strain”.

1. The dimension of strain is?
a) LT-2
b) N/m2
c) N
d) Dimensionless

Explanation: Strain is the ratio of change in dimension to original dimension. So it is dimensionless.

2. What is tensile strain?
a) The ratio of change in length to the original length
b) The ratio of original length to the change in length
c) The ratio of tensile force to the change in length
d) The ratio of change in length to the tensile force applied

Explanation: The tensile stress is the ratio of tensile force to the change i length. It is the stress induced in a body when subjected to two equal and opposite pulls. The ratio of change in length to the original length is the tensile strain.

3. Find the strain of a brass rod of length 250mm which is subjected to a tensile load of 50kN when the extension of rod is equal to 0.3mm?
a) 0.025
b) 0.0012
c) 0.0046
d) 0.0014

Explanation: Strain = dL/L = 0.3/250 = 0.0012.

4. Find the elongation of an steel rod of 100mm length when it is subjected to a tensile strain of 0.005?
a) 0.2mm
b) 0.3mm
c) 0.5mm
d) 0.1mm

Explanation: dL = strain x L = 0.005 x 100 = 0.5mm.

5. A tensile test was conducted on a mild steel bar. The diameter and the gauge length of bat was 3cm and 20cm respectively. The extension was 0.21mm. What is the value to strain?
a) 0.0010
b) 0.00105
c) 0.0105
d) 0.005

Explanation: Strain = dL/L = 0.21/200 = 0.0005.
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6. i) Strain is a fundamental behaviour of a material.
ii) Strain does not have a unit.
a) Both i and ii are true and ii is the correct explanation of i
b) Both i and ii ate true but ii is not the correct explanation of i
c) i is true but ii is false
d) ii is true but i is false

Explanation: Strain is measured in a laboratory that is why it is called a fundamental quantity. Also since it is the ratio of the dimension of length to the dimension of length, it is dimensionless.

7. A tensile test was conducted on a steel bar. The gauge length of the bar was 10cm and the extension was 2mm. What will be the percentage elongation?
a) 0.002
b) 0.02
c) 0.2
d) 2

Explanation: The percentage elongation = dL/L x 100 = 2/100 x 100 = 2.

8. The lateral strain is ___________
a) The ratio of axial deformation to the original length
b) The ratio of deformation in area to the original area
c) The strain at right angles to the direction of applied load
d) The ratio of length of body to the tensile force applied on it

Explanation: The lateral strain is the strain at right angles to the direction of the applied load. The lateral strain is accompanied by the longitudinal strain.

9. The unit of force in S.I. units is ?
a) Kilogram
b) Newton
c) Watt
d) Dyne

Explanation: Force = mass x acceleration = kg x m/s2 = N.

10. Which of the following is not the unit of distance?
a) Angstrom
b) Light year
c) Micron
d) Milestone

Explanation: Milestone means achievement. it is not and unit of distance.

11. A solid cube is subjected to equal normal forces on all its faces. The volumetric strain will be x-times the linear strain in any of the three axes when?
a) X=1
b) X=2
c) X=3
d) X=4

Explanation: The volumetric strain is the change in dimension in three directions and the linear strain depends on the change in only one direction so the volumetric strain is 1 times the linear strain in any of the three directions.

12. A rod 200cm long is subjected to an axial pull due to which it elongates about 2mm. Calculate the amount of strain?
a) 0.001
b) 0.01
c) 0.02
d) 0.002

Explanation: The strain is given by = dL / L = 2/2000 = 0.001.

13. Some structural members subjected to a long time sustained loads deform progressively with time especially at elevated temperatures. What is such a phenomenon called?
a) Fatigue
b) Creep
c) Creep relaxation
d) Fracture

Explanation: Creep is the deformation progressively with time. It comes when the body is subjected to long time load. After the instant deflection due to load, the deformation occurs slowly with time.

14. Find the strain of a brass rod of length 100mm which is subjected to a tensile load of 50kN when the extension of rod is equal to 0.1mm?
a) 0.01
b) 0.001
c) 0.05
d) 0.005

Explanation: Strain = dL/L = 0.1/100 = 0.001.

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