Elasticity

What is Elasticity?

Elasticity refers to the ability of a material to return to its original shape and size after being deformed, once the external force is removed. Materials that exhibit elasticity are capable of withstanding forces that stretch or compress them, provided the elastic limit is not exceeded.

Elastic Modulus

Elastic Modulus (E) = Stress / Strain

The elastic modulus measures the stiffness of a material. The greater the modulus, the stiffer the material. It is a property that characterizes the elasticity of a material.

SI Unit: Pascal (Pa) or N/m²

Types of Elasticity

• Linear Elasticity: Deformation is proportional to the applied force, like in the case of a spring.
• Volumetric Elasticity: When materials undergo change in volume under stress.

Stress and Strain

• Stress: The force applied per unit area (σ = F/A), measured in Pascals (Pa).
• Strain: The deformation produced in a material due to stress (ε = ΔL/L), a dimensionless quantity.

Types of Stress

• Tensile Stress: Stress produced by stretching a material.
• Compressive Stress: Stress produced by compressing a material.
• Shear Stress: Stress produced by forces acting parallel to the surface of the material.

Hooke’s Law

Hooke’s Law: F = kx

Hooke’s law states that the force required to extend or compress a spring is directly proportional to the displacement, provided the elastic limit is not exceeded.

Where F is the force, k is the spring constant, and x is the displacement.

Previous Year Questions

• RRB JE 2018: What does the elastic modulus represent in material science?
• The stiffness of a material
• SSC JE 2019: Which law defines the relationship between force and displacement in elastic materials?
• Hooke’s Law
• HSSC JE 2020: What is the unit of stress?
• Pascals (Pa)

Applications of Elasticity

• Designing of bridges, buildings, and other structures.
• Manufacturing of materials with desirable properties for machinery parts.
• Used in engineering applications like stress analysis, rubber materials, and springs.

Conclusion

Elasticity is a crucial concept in materials science, structural engineering, and physics. It is important for designing safe structures and understanding the behavior of materials under stress. A solid grasp of elasticity and its principles is essential for anyone pursuing a career in physics, engineering, or related fields.