Introduction to Elasticity

Elasticity is the property of a material to regain its original shape and size after the removal of external force. NEET Physics includes elasticity as a key chapter under mechanical properties of solids.

StudentBro notes provide clear explanations, definitions, formulas, and problem-solving techniques to help NEET aspirants understand and apply concepts of elasticity effectively.

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Stress

• Definition: Stress is the internal resistance offered by a body per unit area to deformation caused by external force.

• Formula: Stress = F / A

• Types of stress:

  • Tensile stress – due to stretching

  • Compressive stress – due to compression

  • Shear stress – due to tangential force

• NEET frequently tests conceptual understanding of stress in solids.

Strain

• Definition: Strain is the measure of deformation produced in a material per unit length.

• Formula: Strain = ΔL / L

• Types of strain:

  • Tensile strain – elongation per unit length

  • Compressive strain – shortening per unit length

  • Shear strain – angular deformation

• Strain is a dimensionless quantity and often appears in NEET numerical problems.

Hooke’s Law

• Statement: Within the elastic limit, the stress applied to a body is directly proportional to the strain produced.

• Formula: Stress ∝ Strain or F = kx for a spring

• Hooke’s law is fundamental for solving NEET problems on elastic bodies, springs, and wires.

StudentBro notes emphasize graphical representation of stress-strain curve for better conceptual understanding.

Elastic Moduli

Elasticity of a material is characterized by moduli of elasticity:

1. Young’s Modulus (Y)

   • Measures resistance to tensile or compressive deformation

   • Formula: Y = Tensile Stress / Tensile Strain = (F / A) / (ΔL / L)

   • NEET questions often ask to calculate elongation or compression using Y.

2. Bulk Modulus (K)

   • Measures resistance to volume change under uniform pressure

   • Formula: K = - Pressure / (ΔV / V)

   • Important for problems involving fluids and pressure-induced volume changes.

3. Shear Modulus (η or G)

   • Measures resistance to shear deformation

   • Formula: G = Shear Stress / Shear Strain

   • Useful in NEET for solids subjected to tangential forces.

Poisson’s Ratio

• Definition: Ratio of lateral strain to longitudinal strain in a stretched material

• Formula: σ = Lateral Strain / Longitudinal Strain

• Typical values: 0 < σ < 0.5

• Appears in NEET numerical problems related to elongation and volume change in solids.

Elastic Potential Energy

• Definition: Work done in deforming a body is stored as elastic potential energy.

• For a stretched or compressed wire: U = ½ Stress × Strain × Volume

• For a spring: U = ½ k x²

• NEET questions often involve calculating energy stored in springs or elastic rods.

Stress-Strain Curve

• Elastic limit: Maximum stress where the body returns to its original shape

• Yield point: Stress at which permanent deformation begins

• Ultimate stress: Maximum stress the material can withstand

• Fracture point: Stress at which the material breaks

StudentBro notes explain the curve in detail for NEET aspirants to identify important points.

Relation Between Elastic Moduli

• Relationship among Young’s modulus (Y), Bulk modulus (K), Shear modulus (G), and Poisson’s ratio (σ):
  Y = 2G(1 + σ) = 3K(1 − 2σ)

• Useful for solving NEET problems involving multiple moduli.

Applications of Elasticity in NEET

• Stretching and compression of wires and rods

• Springs and their energy storage

• Understanding mechanical properties of solids in real-life applications

• Stress analysis in beams, bridges, and structures

Mastery of elasticity ensures aspirants can solve both theoretical and numerical questions effectively.

Tips for NEET Preparation on Elasticity

1. Memorize definitions and formulas for stress, strain, and all elastic moduli.

2. Practice stress-strain curve identification and interpretation.

3. Solve numerical problems on elongation, volume change, and shear deformation.

4. Understand elastic potential energy calculations for wires and springs.

5. Relate conceptual understanding with real-life examples to retain formulas better.

StudentBro notes are structured to help aspirants implement these tips effectively.

Advantages of StudentBro NEET Physics Notes

• Covers stress, strain, Hooke’s law, elastic moduli, Poisson’s ratio, and elastic potential energy

• Step-by-step examples and diagrams included for clarity

• Structured for easy revision and conceptual understanding

• Focused on NEET syllabus and high-yield problems

These notes ensure aspirants can confidently tackle elasticity questions in NEET exams.

Conclusion

The chapter Elasticity is a crucial part of NEET Physics under mechanical properties of solids. Mastery of stress, strain, Hooke’s law, elastic moduli, Poisson’s ratio, and elastic potential energy is essential for solving conceptual and numerical problems.

StudentBro NEET Physics notes provide structured, clear, and exam-focused guidance, enabling aspirants to confidently solve elasticity problems and excel in NEET exams.