Stress - Definition And Types

What is Stress?

We can define stress as the force per unit area applied to a material. The maximum amount of stress a material can stand before it breaks is called the breaking stress. Internal restoring forces cause the elastic bodies to regain their initial shape. If we try to compute this restoring force that acts on per unit area of a misshapen body it will be termed as stress.

Types of Stress

There are several different types of stress in physics but mainly it is categorized into two forms that are Normal Stress and Tangential or Shearing Stress. Some stress types are discussed in the points below.

Normal Stress:

It may be called a normal stress when, as the name already tells us, the stress applied is perpendicular to the body. The length of the wire or the volume of the body changes stress will be at normal.

Longitudinal Stress:

When the length of the body changes by the normal stress that is applied to it is termed as Longitudinal Stress

Longitudinal Stress = Deforming Force / Area of cross section   =  F/A

There can be a further categorization under the longitudinal stress which divides it into two sorts. Tensile stress can be observed when a rod or wire is stretched by its two ends under Newton’s third law of motion. Compression will be acting on the rod that is pushed by opposite and equal forces at its two ends. This form of stress is termed as compressive stress.

Bulk Stress or Volume Stress:

When the volume of body changes due to the stress it is termed as Volume stress. A body that is under the force of pressure P, when submerged in a liquid, the body confronts a force that at any time is perpendicular or normal to the surface of the object. The area that the force is acting on is directly proportional to the magnitude of the force.

Bulk Stress =    Force/Area= Pressure

Shearing Stress:

When the forces being applied on the surface is parallel to it and thus the stress that’s acting on the surface also plots a tangent. This kind of stress is termed as a shearing or tangential stress. The shape of the body changes:

Shearing Stress = Force / Surface Area = F / A

Tensile Stress:

If the stress applied causes an increase in the body’s length because of the force the stress is termed as tensile stress.

Compression Stress:

The shape of the body changes due to the tangential stress that is applied which is due to the change in volume or length of the body.

Tangential Stress:

When the force that is exerted is tangential to the surface it’s being applied on and transforms the body.

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Practise This Question

A heavy mass is attached to a thin wire and is whirled in a vertical circle. The wire is most likely to break.