IIT JEEmains physics notes 2023 properties of solids

PROPERTIES OF SOLIDS AND LIQUIDS




SOLID & ELASTICITY
Stress, Strain and Elastic Moduli
Stress : Restoring force developed/Area.
Strain : Change in dimension/original dimension.
Stress
Modulus of Elasticity = Strain


 Greater is modulus of elasticity greater is the stress
developed i.e., greater is the restoring force.




Young’s Modulus
Young’s modulus is a measure of the resistance of a solid
to a change in its length when a force is applied
perpendicular to a face.



1

, Young’s modulus Y for the material of the rod is defined
as the ratio of tensile stress to tensile strain.
so
Tensile stress
Young’s Modulus =
Tensile strain

 Fn / A Fn Lo
Y= = =
 L / Lo AL


Shear Modulus


The shear stress is defined as
Tangetial force
Shear Stress =
Area


= F t

A

Where A is the area of the surface.



Bulk Modulus
Normal or compressive stress P
Bulk modulus of elasticity K
Volumetric strain
 V
V
or
dP
K  V
dV
1
Compressibility = K


2

, Density and Pressure
The density of a substance is defined as the mass per unit
volume of a sample of the substance.
M
=
V

The SI units of density are kg m-3.



Specific Gravity
The specific gravity of a substance is the ratio of its
density to that of water at 4oC, which is 1000 kg/m3.
Specific gravity is a dimensionless quantity numerically
equal to the density quoted in g/cm3. For example, the
specific gravity of mercury is 13.6, and the specific gravity
of water at 100oC is 0.998.




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