# Mechanical Properties of Solids, Class 11 Physics | SwaVid

Mechanical Properties of Solids, NCERT Class 11 Physics: notes with key ideas, formulas, common mistakes and 3 quick checks with worked answers.

Canonical: https://www.swavid.com/cbse/class-11/physics/chapter/mechanical-properties-of-solids

Source: https://www.swavid.com/cbse/class-11/physics/chapter/mechanical-properties-of-solids

# Mechanical Properties of Solids

## Formulas and definitions

## Key ideas

## Common mistakes

## Quick checks

## Keep going

## Questions parents ask

## Class 11 Physics on SwaVid

### Elasticity and plasticity

### Stress and strain

### Hooke's law and stress-strain curve

### Elastic moduli

### Next chapter

### Related chapter

### All chapters

SwaVid › CBSE › Class 11 › Physics › Mechanical Properties of Solids

Notes written by SwaVid from the NCERT textbook.

Class 11 Physics, Chapter 8. Key ideas, formulas and common mistakes.

CBSE prints 20 marks for Units VII-IX together, not for this chapter alone.

Short answer. This chapter explains how solid bodies deform when external forces act on them and recover their shape when deforming forces are removed. It introduces concepts of stress, strain, Hooke's law, and elastic moduli.

Source: NCERT Physics Part II (Reprint 2026-27) , Chapter 8, Mechanical Properties of Solids

A body that regains its original shape and size after the removal of deforming forces is called elastic. A body that does not regain its original shape and retains deformation is called plastic.

Stress is the restoring force per unit area developed inside a deformed body. Strain is the fractional change in dimension produced by the deforming force, and it is a dimensionless quantity.

For small deformations, stress is directly proportional to strain. A typical stress-strain curve shows regions of proportionality, yield point, ultimate tensile strength, and fracture point.

The ratio of stress to strain within the elastic limit is called the modulus of elasticity. The three primary moduli are Young's modulus for length, shear modulus for shape, and bulk modulus for volume.

Try each question first. Then tap it to see the answer.

Stress = F / A = 100 / (1.0 × 10⁻⁶) = 1.0 × 10⁸ N m⁻²

Strain = ΔL / L = (1.0 × 10⁻³) / 2.0 = 5.0 × 10⁻⁴

Y = Stress / Strain = (1.0 × 10⁸) / (5.0 × 10⁻⁴) = 2.0 × 10¹¹ N m⁻²

2.0 × 10¹¹ N m⁻²

Volume strain = -ΔV / V = (5.0 × 10⁻⁵) / 0.5 = 1.0 × 10⁻⁴

B = p / (volume strain) = (1.0 × 10⁶) / (1.0 × 10⁻⁴) = 1.0 × 10¹⁰ N m⁻²

1.0 × 10¹⁰ N m⁻²

Area of top face A = 0.1 × 0.1 = 0.01 m²

Shearing stress = F / A = 1000 / 0.01 = 1.0 × 10⁵ N m⁻²

Shear strain θ = Stress / G = (1.0 × 10⁵) / (2.0 × 10¹⁰) = 5.0 × 10⁻⁶

5.0 × 10⁻⁶

Mechanical Properties of Fluids .

Laws of Motion .

The 14 chapters of Class 11 Physics .

CBSE does not give marks to one chapter. It prints 20 marks for Units VII-IX together (Properties of Bulk Matter; Thermodynamics; Behaviour of Perfect Gases and Kinetic Theory). Mechanical Properties of Solids is part of that group.

No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed.

Mechanical Properties of Fluids.

SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works.

- Ch 8 NCERT book
- 20 marks, Units VII-IX together
- 3 quick checks
- Assigning units to strain . Strain is a ratio of two identical physical quantities such as length or volume. It is dimensionless and has no units.
- Treating stress simply as applied pressure or force without area . Stress is an internal restoring force per unit area developed due to deformation, not just external force applied on the body.
- Forgetting the negative sign in the bulk modulus formula . An increase in pressure causes a decrease in volume, so ΔV is negative. The negative sign is placed in B = -p / (ΔV / V) to keep B positive.

## Key Links

- [CBSE](https://www.swavid.com/cbse)
- [Class 11](https://www.swavid.com/cbse/class-11)
- [Physics](https://www.swavid.com/cbse/class-11/physics/chapters)
- [Start free →](https://www.swavid.com/signup)
- [All 14 chapters](https://www.swavid.com/cbse/class-11/physics/chapters)
- [NCERT Physics Part II (Reprint 2026-27)](https://ncert.nic.in/textbook.php)
- [Open notes](https://www.swavid.com/cbse/class-11/physics/chapter/mechanical-properties-of-fluids)
- [Open notes](https://www.swavid.com/cbse/class-11/physics/chapter/laws-of-motion)
- [Class 11 Physics](https://www.swavid.com/cbse/class-11/physics/chapters)
- [Start free →](https://www.swavid.com/signup)