The **key difference** between stress and strain in physics is that **stress is the force experienced by an object that causes a change in the object, whereas strain is the change in the shape of the object when stress is applied**.

Stress and strain in physics are related to each other, and they are directly proportional to each other up to the elastic limit of an object. The relationship between stress and strain can be given using Hooke’s law.

### CONTENTS

1. Overview and Key Difference

2. What is Stress in Physics

3. What is Strain in Physics

4. Stress vs Strain in Tabular Form

5. Comparison Summary

## What is Stress in Physics?

Stress is the force experienced by an object which can cause a change in the object. It is the force applied per unit area of an object. We can give the stress in physics as follows:

σ= F/A

When σ is stress, F is the force applied, and A is the area of the force application. The unit of measurement of stress is N/m^{2}. There are two types of stress: they are tensile stress and compressive stress. Tensile stress is the force that acts on a unit area of material that can result in an increase in the length of the object. Therefore, the objects that are under tensile stress can become thinner and longer.

Compressive stress is the force acting on a unit area which can result in the decrease of length of the object. Therefore, the objects that are under this stress can become thicker and shorter.

## What is Strain in Physics?

Strain is the change in the shape of an object when stress is applied. Therefore, we can define it as the amount of deformation that is experienced by an object according to the direction of force applied, divided by the initial dimensions of the body. The relationship between these terms can be given as follows:

ε= δl/L

ε is the strain that occurs due to stress, while l is the change in the length, and L is the original length of that object. The strain of an object is a dimensionless property (a length is divided by another length). We can give it a relative change in shape.

There are two types of strain: tensile strain and compressive strain. The tensile strain occurs due to tensile stress, while compressive strain occurs due to compressive stress.

## What is the Difference Between Stress and Strain in Physics?

Stress and strain in physics are related to each other, and they are directly proportional to each other up to the elastic limit of an object. The relationship between stress and strain can be given using Hooke’s law. The key difference between stress and strain in physics is that stress is the force experienced by an object which causes a change in the object, whereas strain is the change in the shape of the object when stress is applied. Moreover, stress is measurable and has a unit of measurement, while strain is a dimensionless quantity and has no unit.

Below is a summary of the differences between stress and strain in tabular form.

## Comparison Summary – Stress vs Strain in Physics

Stress and strain in physics are related to each other, and they are directly proportional to each other up to the elastic limit of an object. The relationship between these two terms can be given using Hooke’s law. The key difference between stress and strain in physics is that stress is the force experienced by an object which causes a change in the object, whereas strain is the change in the shape of the object when stress is applied.

##### Reference:

1. “Stress and Strain – Definition, Stress-Strain Curve, Hooke’s Law, SI Units.” *BYJUS*, BYJU’S, 24 Feb. 2021, Available here.

##### Image Courtesy:

1. “Stress Strain Ductile Material” By Breakeydown (CC BY-SA 3.0) via Commons Wikimedia

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