K = FV / A ΔV = & DElta; p V / V where, Δp = F / A = Change in pressure.
Its unit is N / m 2 or Pascal and its dimensional formula is [ ML-1 T-2 ]. 3. Modulus of Rigidity( η)
It is defined as the ratio of tangential stress to the shearing strain, within the elastic limit.
η = Tangential stress / Shearing strain Its urut is N / m 2 or Pascal and its dimensional formula is [ ML-1 T-2 ]. Compressibility Compressibility of a material is the reciprocal of its bulk modulus of elasticity. Compressibility( C) = 1 / k Its SI unit is N-1 m 2 and CGS unit is dyne-1 cm 2.
Steel is more elastic than rubber. Solids are more elastic and gases are least elastic.
For liquids. modulus of rigidity is zero. Young’ s modulus( Y) and modulus of rigidity( η) are possessed by solid materials only.
Limit of Elasticity
The maximum value of deforming force for which elasticity is present in the body is called its limit of elasticity.
Breaking Stress
The minimum value of stress required to break a wire, is called breaking stress.
Breaking stress is fixed for a material but breaking force varies with area of cross-section of the wire.
Safety factor = Breaking stress / Working stress