3. What is Elasticity ??
• The ability of a deformed material body
to return its original shape and size when
the forces causing the deformation are
removed is called elasticity
Rubber Band
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4. Elastic Properties of Matter
•An elastic body is one that returns
to its original shape after a
deformation.
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5. Elastic Properties of Matter
•An inelastic body is one that does
not return to its original shape after
a deformation
Inelastic Ball
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6. An Elastic Spring
• A spring is an example of an
elastic body that can be
deformed by stretching.
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8. Strain
• It is the ratio of change in configuration to the
original configuration of the deformed body. It has
neither unit nor dimension.
• 1 ) Tensile Strain
• 2 ) Volumetric Strain
• 3 ) Shear Strain
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9. Youngs Modulus
• It is the ratio of longitudinal stress to the
longitudinal strain.
• Young’s modulus = longitudinal stress / longitudinal strain
• Y = ( FL ) / ( ΔLπr2)
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10. • “Within the elastic
limit the stress is
directly proportional
to the strain”.
• Stress ∝ strain
Hook’s Law
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11. Poisson’s Ratio
• Within the elastic limit, the
ratio between lateral strain
and linear strain is a constant.
This constant is called as
poisson’s ratio. It is
represented by 𝝈.
• 𝝈 = lateral strain / linear strain
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