Stress and strain are two important parameters associated with a body that is subjected to an external force.

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The force of resistance per unit area of the body is called stress. It is measured as the ratio of force and the area of the cross-section. The external force acting on the body is termed as

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These are of 4 Types:

### Strength of Material

When a body is subjected to some external force, it undergoes some form of deformation. The resistance of the body to prevent such deformation forms the**strength of the material.**### What is Stress?

**load (P).**If the area of cross-section is (A), then stress is given by,**Ïƒ = P/A**

### Unit of Stress

The unit of stress is N/m2 or kgf/m2 or kgf/cm2.

The S.I Unit is N/m2. Where, 1N/m2 = 1 Pascal

### What is a Strain?

The ratio of change in dimension of the body to its original dimension is called strain. The strain is a unitless quantity. Which is given by the relation,

**Îµ = ∆l/l**

∆l = Change in Dimension

l = Original Dimension

- Tensile Strain
- Compressive Strain
- Volumetric Strain
- Shear Strain

#### 1. Tensile Strain

This is the ratio of change in length of the body to its original length due to the deformation caused by a pulling force or tensile force.

e = dl/l

e = dl/l

#### 2. Compressive Strain

This is the ratio of change in dimension of the body to the original dimension due to the deformation caused by a pushing force or compressive force.

e = -dl/l

e = -dl/l

#### 3. Volumetric Strain

This is the ratio of change in the volume of the body to its original volume.

e = dV/V

e = dV/V