SHRI AGRESEN VIDHALAYA. Project report on:- ELASTICITY. Submited by:- Guided by:- Ishita Agrawal Purva Mishra . Acknowledgement.
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I take opportunity to express my deep sense of gratitude and thank to miss Purva Mishra teacher of physics of Shri Agresen Vidhalaya for giving guidance in this project work . Her enormous contribution towards my project ‘elasticity’. Her continuous guidance throughout project and very friendly and useful approach, I will never forget.
I also thank Mrs.. Mradula Patni for her encouragement for this work.
Student of class 11th (p.c.m)
This is to certify that Ishita Agrawal of class 11thB in the session 2007-2008 of this school has completed the project ‘Elasticity’.
she has submitted a complete and satisfactory account of the same.
Subject teacher Principle
Miss Purva Mishra Mrs. Mradula Patni
Types of stress
Types of Strain
Modulus of Elasticity
Modulus of rigidity
Work done in stretching a wire
Some other terms related to Elasticity
1. Elastic limit
2.Elstic after effect
3. Elastic fatigue
Some conceptual question’s
Elasticity is a branch of physics which studies the properties of elastic materials. A material is said to be elastic if it deforms under stress (e.g., external forces), but then returns to its original shape when the stress is removed. The amount of deformation is called the strain.
3. Shear Strain:-When change takes place in the shape of the body, the strain is called shear strain.
i.e. Stress=E*Strain (where E is constant called modulus of Elasticity or coeffient of elasticity.)
σ =lateral strain (β)
longitudinal strain (α)
σ = d*L
σ = β
This is the expression for stretching force
W=1/2 YAl/L . l
This work done is converted into potential energy (U).
U=1/2 extension*stretching force
U=YAl² * L [f/A=Yl/L]
U=1/2 .Yl/L .l/L.AL
since volume = 1
Q.1 Explain why solids are more elastic than gases?
(Ans) The solids are more elastic than gases because for a given stress, the gases are more compressible than solids.
Q.2 Which is more elastic: water or air, why?
(Ans) Water is more elastic then air, because bulk modulus of elasticity is reciprocal of compressibility than water.
Q.3 Why does spring balance shows wrong reading after long use ?(Ans) The spring will lose its elastic character due to long use .Q.4 Why a spring is made of steel and not of copper ?(Ans) Under a given deforming force , the steel spring is stretched more than copper spring . Moreover the steel spring recovers its original state quicker than copper after the removal of deforming force.Q.5Crystalline solids are called true solids. why?(Ans)Bcoz they have a well defined, regularly repeated three dimensional arrangement of ions in crystalline solids.
Q.1The young’s modulus of the material of a wire is 6X1012N/m2 and there is no transverse strain in it. Find its modulus of rigidity?
(Ans) Modulus of rigidity is given by
Q.2The breaking stress of aluminum is 8.1X107Nm-2. Find the greatest length of aluminum wire that can hang vertically without breaking. Density of aluminum is 2.7X103 kgm-3.(Ans) Let a = area of cross section and l= length of wire which can be suspended Mass of the wire, m=volume X densityCont…………..
Q.3Two wires A and B of the same material have radii in the ratio 2:1 and lengths in the ratio 4:1. Find the ratio of the normal forces required to produce the same change in the lengths of the two wires?(Ans) Given radii are 2:1 and lengths are 4:1 Cont………………
Q.4Find the maximum length of steel wire that can hang without breaking. Breaking stress=7.9X1012dyne/cm2. Density of steel =7.9g/cc(Ans) Cont……………..
Q.5 A long spring is stretched by 2 cm and its potential energy is V. Find the potential energy of the spring if it is stretched by 10 cm?(Ans) Potential energy of the stretched springCont……………..