Mechanism of Solid-Part-II : By R.Buvana Mechanism of Solid-Part-II
Mechanism of Solids-Part-II : Mechanism of Solids-Part-II Elasticity
Stress and Strain
Hook’s law and Modulus of Elasticity
Poisson’s Ratio
Elastic after effect
Elastic fatigue
Elastic potential energy stored in a stretched wire.
Elastic constants
Few Numerical related to Elasticity
Elastic after effect : Elastic after effect The delay in regaining the original configuration by the bodies on the removal of deforming force is called elastic after effect.
The elastic after effect is negligibly small for quartz fibre and phosphor-bronze. For this reason ,the suspensions made from quartz and phosphor-bronze are used in galvanometers and electrometers.
Elastic Fatigue : Elastic Fatigue The loss of strength of the material due to repeated strains on the material is called elastic fatigue.
That is why bridges are declared unsafe after a long time of their use.
Elastic Potential Energy stored in a stretched wire : Elastic Potential Energy stored in a stretched wire Consider a wire of length L and area of cross section A.Let l be the length which the wire is stretched.
Y=F/A/l/L
Dw=Fdl =YAl/L dl, F=YAl/L
? dw=?YAl/L dl
W=1/2 Fx l
W=1/2 x Stretching force x extension
Slide 6 :
Elastic Constants : Elastic Constants 9/Y = 3/? +1/K
Y=3K(1-2s)
Y=2?(1+s)
s=3K-2? /6K+2?)
Y=young’s modulus
K=Bulk modulus
?=modulus of rigidity
s=poisson’s ratio
Home work questions : Home work questions 1.One end of a steel wire of length 1.5 m us rigidly fixed with the roof of a house and a mass of 4.0 kg is suspended with the free end of this wire as shown in figure. one end of another wire(made of brass) of length 1.0 m is attached to mass of 4.0 kg and a mass of 6.0 kg is suspended from the free end of the brass wire. Calculate the elongation of the steel and brass wire. Given, diameter of each wire=.25cm.Y=2x10¹¹ N/m² Y of brass is 9.1x10¹°N/m².