2 Mark Questions and Answers: 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.
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