Upld Flascard 16 Modulus Of Elasticity

Card # 16

Modulus of Elasticity

Young’s Modulus Young’s modulus is the force required to extend a wire of unit length and unit area of cross section through unity in case of wire.

FL Al A = 1m2 , L = 1m, l = 1m

γ=

Then γ = F

If for a given wire area of cross section = A= π r 2 weight applied F= mg

γ=

FL mgL γ= 2 πr l Al ,

Young’s modulus is related to solids only. Modulus of Compressibility β The reciprocal of bulk modulus is called compressibility. Compressibility β = 1/K = -ΔV/PV It is more effective in gases.

= Poisson’s Ratio σ When a deforming force is applied on a wire its length increases but its diameter decreases, this section is produced perpendicular to its length is called lateral strain. β=d/D =Change in diameter/Original diameter α=l/L=Change in length/Original Length σ=β/α=Lateral Strain/Longitudinal Strain σ Poisson’s ratio has no limit. σ = α L Dl