CE 1202 – MECHANICS OF SOLIDS B.E. II Yr Civil Engineering Two Marks Question and Answers unit-1

UNIT –1
STRESS STRAIN AND DEFORMATION OF SOLIDS, STATES OF STRESS
1. Define stress.
When an external force acts on a body, it undergoes deformation. At the same
time the body resists deformation. The magnitude of the resisting force is numerically
equal to the applied force. This internal resisting force per unit area is called stress.
Stress = Force/Area
When a body is subjected to an external force, there is some change of dimension in the
body. Numerically the strain is equal to the ratio of change in length to the original length
of the body.= P/A unit is N/mm^2
2. Define strain
Strain = Change in length/Original length
e = L/L
3. State Hooke’s law.
It states that when a material is loaded, within its elastic limit, the stress is
directly proportional to the strain.
Stress Strain
e
= Ee
E = /e unit is N/mm^2
Where,
E - Young’s modulus
- Stress
e - Strain
4. Define shear stress and shear strain.
The two equal and opposite force act tangentially on any cross sectional plane of
the body tending to slide one part of the body over the other part. The stress induced is
called shear stress and the corresponding strain is known as shear strain.
5. Define Poisson’s ratio.
When a body is stressed, within its elastic limit, the ratio of lateral strain to the
longitudinal strain is constant for a given material.
Poisson’ ratio (μ or 1/m) = Lateral strain /Longitudinal strain
6. State the relationship between Young’s Modulus and Modulus of Rigidity.
E = 2G (1+1/m)
Where,
E - Young’s Modulus
K - Bulk Modulus
1/m - Poisson’s ratio
7. Define strain energy
Whenever a body is strained, some amount of energy is absorbed in the body. The
energy which is absorbed in the body due to straining effect is known as strain energy.
8. Give the relationship between Bulk Modulus and Young’s Modulus.
E = 3K (1-2/m)
Where,
E - Young’s Modulus
K - Bulk Modulus
1/m - Poisson’s ratio
9. What is compound bar?
A composite bar composed of two or more different materials joined together
such that system is elongated or compressed in a single unit.
10. Define- elastic limit
Some external force is acting on the body, the body tends to deformation. If the
force is released from the body its regain to the original position. This is called elastic
limit
11. Define – Young’s modulus
The ratio of stress and strain is constant with in the elastic limit.
E = Stress
Strain
12. Define Bulk-modulus
The ratio of direct stress to volumetric strain.
K = Direct stress
Volumetric strain
13. Define- lateral strain
When a body is subjected to axial load P. The length of the body is increased. The
axial deformation of the length of the body is called lateral strain.
13. Define- longitudinal strain
The strain right angle to the direction of the applied load is called lateral strain.
14. What is principle of super position?
The resultant deformation of the body is equal to the algebric sum of the
deformation of the individual section. Such principle is called as principle of super
position
15. Define- Rigidity modulus
The shear stress is directly proportional to shear strain.
N = Shear stress
Shear strain
16. State principle plane.
The planes, which have no shear stress, are known as principal planes. These
planes carry only normal stresses.
17. Define principle stresses and principle plane.
Principle stress: The magnitude of normal stress, acting on a principal plane is
known as principal stresses.
Principle plane: The planes which have no shear stress are known as principal
planes.
18. What is the radius of Mohr’s circle?
Radius of Mohr’s circle is equal to the maximum shear stress.
19. What is the use of Mohr’s circle?
To find out the normal, resultant stresses and principle stress and their planes.
20. List the methods to find the stresses in oblique plane?
1. Analytical method
2. Graphical method