AP Inter 1st Year Physics Notes Chapter 10 Mechanical Properties of Solids

Students can go through AP Inter 1st Year Physics Notes 10th Lesson Mechanical Properties of Solids will help students in revising the entire concepts quickly.

AP Inter 1st Year Physics Notes 10th Lesson Mechanical Properties of Solids

→ The property of a body by virtue of which it resists the deformation forces and regains its original shape when the deformation forces are removed is called elasticity.

→ The restoring force per unit area developed inside the body is called stress.
∴ Stress = \(\frac{\text { Restoring force }}{\text { Area }}=\frac{R}{A}\)

→ The maximum value of stress within which a body completely regains its original condition when the deforming forces are removed is called its elastic limit.

→ Hooke’s law: Within the proportionality limit, the stress is directly proportional to the strain produced in a body. Stress × strain = constant within elastic limit.

→ The ratio of increase in length of a wire to its original length is called tensile or longitudinal or linear strain.
Linear strain = \(\frac{\Delta \mathrm{l}}{\mathrm{L}}=\frac{\mathrm{e}}{\mathrm{L}}\)

→ The ratio of the relative displacement between two layers to the distance between them is called shearing strain, θ.

AP Inter 1st Year Physics Notes Chapter 10 Mechanical Properties of Solids

→ The volume strain or bulk strain in the ratio of change in volume to its original volume.
i. e., Bulk strain = \(\frac{\Delta V}{V}\).

→ Within elastic limit of a body, the ratio of linear stress to linear strain is called Youngs modulus of elasticity Y. Y = \(\frac{F}{A} / \frac{e}{L}=\frac{F}{A} \cdot \frac{L}{e}\)

→ Within the elastic limit of a body, the ratio of shearing stress to shearing strain is called rigidity modulus of elasticity (G). .
∴ Rigidity modulus G = \(\frac{F / A}{\theta}=\frac{F}{A \theta}\)

→ Within the elastic limit of a body, the ratio of bulk stress to bulk strain is called bulk modulus of elasticity B.
PV = –\(\frac{\mathrm{PV}}{\Delta \mathrm{V}}\)

→ When a body is subjected to continuous elastic straining for some time, it appears to have lost its elastic nature temporary which it regains after taking sufficient rest. This behaviour is called elastic fatigue.

→ The ratio of lateral contractional strain to longitudinal elongational strain for the same stress is called Poisson’s ratio σ.

→ Shearing strain = 2 × longitudinal strain

→ Bulk strain = 3 × longitudinal strain

→ Hooke’s law is valid only in the linear part of stress – strain curve.

→ The young’s modulus and shear modulur are relevant only for solids. Bulk modulus is relevant for solids, liquids and gases.

AP Inter 1st Year Physics Notes Chapter 10 Mechanical Properties of Solids

→ Metals have larger values of young’s modulus than alloys and elastomes.

→ Examples of ductile metals are, Copper, Aluminium, lead, gold, Examples of brittle metals are ; Glass ceramic

→ Strain energy is the energy stored in a body due to its deformation.

→ Stress is not a vector quantity.

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