elasticity formula

One Mark Questions With Answers1. What is a rigid body ?A body which experiences a small deformation when a sufficiently large force is applied is considered to be rigid.2. When is a body said to be perfectly elastic ?A body is said to be perfectly elastic if it tends to resist deformation. It recovers completely from the deformation once the deforming force is removed.3. When is a body said to be perfectly plastic ?If a body does not recover its original state when the external force is removed but retains its altered state, it is said to be perfectly plastic.4. Define stress.When an external force F is applied uniformly over a surface of area A then the force per unit area is called stress. (Stress = F/A)5. Define strain.The fractional change in the dimension of a body produced by the external force acting on itis known as strain.6. What is the SL unit of stress ?SI unit of stress is Nm~2.7. What is the dimensional formula for stress ?[stress] = [M'L-'r2]8. What is the SI unit of strain ?Strain has no unit.9. State Hooke's law.The law states that, provided the strain is small stress is directly proportional to strain.10. Define coefficient of elasticity.It is the ratio of stress to strain.11. Define Young's modulus.It is the ratio of stress to longitudinal strain.12. What is the SI unit of Young's modulus ?SI unit of Young's modulus is Nm~2.13. What is the dimensional formula for Young's modulus.[Young's modulus] = [M1 L_1T~2]14. Define Rigidity modulus.Rigidity modulus is defined as the ratio of tangential stress to shearing strain.15. What is the SI unit of* Rigidity modulus ?SI unit of rigidity modulus is Nnr2.16. Define Bulk modulus.It is the ratio of stress to volume strain.17. What is the SI unit of bulk modulus.SI unit of bulk modulus is Mm"2.18. What is the dimensional formula of Bulk modulus.[Bulk modulus] = [MW2] Two Marks Questions1. What is elasticity ?2. Distinguish between elastic and plastic materials.3. State and explain Hooke's law.4. Define stress and strain.5. Explain why a rubber tube is longer when suspended vertically than when placed horizontally on a table.6. If the stress to which a wire is subjected is equal to the Young's modulus of its material, find the relation between the initial and final lengths of the wire.Five Marks Questions1. State and explain Hooke's law. Explain the terms elastic limit, yield point and breaking stress.2. Define the three moduli of elasticity. What is the SI unit of the modulus of elasticity ?3. Explain the terms stress and strain.