Modern Physics

# Difference Between Stress and Strain in Tabular Form

The basic difference between stress and strain is that stress is the deforming force per unit area. Its unit is the same as pressure which is N/m²,While strain is the apparent change in the shape, volume or length of object caused due to stress is called strain. Strain has no unit.

## Stress

It is defined as the force applied to the unit area to produce a change in the shape, volume or length of a body. Mathematically it is expressed as:

The SI unit of stress (σ) is newton per square meter (Nm-2), which is given the name pascal  (pa).

## Types of stress

Stress may cause a change in length, volume, and shape.

• ### Tensile stress

When stress changes the length, it is called tensile stress.

• ### Compressional stress

When stress changes its volume, it is called compressional stress.

• ### Shear stress

When stress changes the shape, it is called shear stress.

## Strain

The strain is a measure of the deformation of a solid when stress is applied to it. In the case of deformation in one-dimensional strain is defined as the fractional change in length. If Δl is the change in length and l is the original length, then strain is given by:

## Types of strain

Since strain is the ratio of lengths, it is dimensionless, and therefore, has no units.

### Tensile strain

If the strain is ε is due to tensile stress σ, it is called tensile strain.

### Compressive strain

If the strain is produced as a result of compressive stress, it is called compressive strain.

### Volumetric strain

When the applied stress changes the volume, the change in volume per unit volume is known as volumetric strain.

### Shear strain

When the opposite faces of a rigid cube are subjected to shear stress.

## Stress Vs Strain

 Stress Strain Stress is the restoring or deforming force per unit area. The strain is the change in shape per original shape. Its formula is  σ = F/A Its formula is  ∈ = ΔL/L Its unit is N/m² It has no unit