Stress - Definition, Unit, Types, FAQs

Stress - Definition, Unit, Types, FAQs

Edited By Team Careers360 | Updated on Nov 12, 2024 02:20 AM IST

What is Stress?

Stress definition is, the force that acts on a body of per unit area. The effect of stress causes strain in the material. Stress is the process which helps to deform the material. Stress in physics, helps us to understand the force that a material or object experiences.

What is the unit of stress?

Stress meaning, the force that acts on a material in a unit area.

So, the unit of stress is,

Stress=ForceArea=Nm2

Hence, we get the SI unit of stress is Nm2 and in cgs unit of stress is dynecm2.

Also read -

Types of Stress

A. Tensile Stress or Normal Stress

The tensile stress definition is given below-

The external force per unit area of material resulting in stretch of material is known as tensile stress. We say that object is in tension. The subscript is a reminder that force acts perpendicular to cross-section.

Tensile Stress or Normal Stress

We define tensile stress at cross-section as ratio of force F to cross-sectional area A:

Normal stress=FA----(1)

This is a scalar quantity. The SI unit of stress is pascal. Equation (1) shows that 1 pascal equals 1 newton per square metre (N/m²) :

1 pascal = 1 Pa = 1 N/m²

The unit of stress is same as that of pressure. Air pressure in automobile tyres is typically around 300 kPa.

Also read :

B. Shear stress or tangential stress

Figure shows a body being deformed by shear stress. A force acting in generally horizontal direction especially or force that produces mountain folding and overthrusting.

Shear stress or tangential stress

Shear stress or Tangential stress=FA.

C. Bulk stress or Volumetric stress

Thus, bulk stress or volume stress is also can be called as pressure.

Bulk stress or Volume stress=p=FA.

Bulk stress or Volumetric stress

Hooke’s Law

Hooke’s Law is defined as the ratio of stress to strain.

StressStrain=Hooke's Law (Elastic Modulus)

The relation between stress and modulus of elasticity:

  1. Young's Modulus Y=Tensile stress or Normal stressTensile strain or normal strain
  2. Shear Modulus G=Shear stress or tangential stressShear strain or tangential strain
  3. Bulk Modulus B=Normal stressVolume strain
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Thermal stress

The stress which is developed due to the rise or fall in temperature is known as thermal stress.

Let us consider that a rod of length L is fixed between two rigid walls and is heated to raise the temperature by ∆θ . Hence, due to rise in temperature, there develops a strain which is represented by ∆LL.

From Young’s Modulus Y=Stress/Strain

We get, Stress=Y×Strain=Y∆L/L.

Relation between Stress and Elastic Potential Energy

Elastic Potential energy is defined as total work which is done against the restoring force that stretches a material by any length.

The relation with stress is,

Elastic Potential Energy U=12Stress×Strain

Also check-

NCERT Physics Notes :

Frequently Asked Questions (FAQs)

1. Define stress in physics.

Stress meaning in physics, is the amount of force that acts on any material with unit surface area. It is the property by which we can understand the limit of deformation of any material.

2. What is the SI unit of stress?

The SI unit of stress is Nm2. The SI unit of stress is also considered to be Pascal.

3. What are the different types of stress?

There are mainly three types of stress in physics-

  1. Tensile stress or Normal stress: Tensile stress or normal stress is defined as the stress, when the force F acts normal to the surface of the material to a cross-sectional area A. The formula of tensile or normal or longitudinal stress is, Normal stress=FA. Normal stress is also known as longitudinal stress.

  2. Shear Stress or Tangential stress: Shear stress or tangential stress is defined as the stress where the forces F act tangentially to the opposite ends of an object of surface area A. The formula of shear or tangential stress is, Tangential Stress=FA.

  3. Bulk stress or Volumetric stress: Bulk stress or volume stress is defined as the force which acts tangentially on the surface of a body which causes a change in its volume or pressure. This stress symbol is, ∆p where p is pressure which can be written as p=F/A.

4. What is hoop stress formula?

The hoop stress formula is H=PDm/2t where, H= hoop stress, P = pressure, t = thickness of the pipe and Dm = diameter of the pipe.

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Questions related to

Get answers from students and experts

Question :  Read the passage given below and answer the question that follows:
Once upon a time, a psychology professor walked around on a stage while teaching stress management principles to an auditorium filled with students. As she raised a glass of water, everyone expected they'd be asked the typical "glass half empty or glass half full" question. Instead, with a smile on her face, the professor asked, "How heavy is this glass of water I'm holding?" Students shouted out answers ranging from eight ounces to a couple of pounds. She replied, "From my perspective, the absolute weight of this glass doesn't matter. It all depends on how long I hold it.

If I hold it for a minute or two, it's fairly light. If I hold it for an hour straight, its weight might make my arm ache a little. If I hold it for a day straight, my arm will likely cramp up and feel completely numb and paralyzed, forcing me to drop the glass to the floor. In each case, the weight of the glass doesn't change, but the longer I hold it, the heavier it feels to me." As the class shook their heads in agreement, she continued, "Your stresses and worries in life are very much like this glass of water. Think about them for a while and nothing happens. Think about them a bit longer and you begin to ache a little. Think about them all day long, and you will feel completely numb and paralyzed incapable of doing anything else until you drop them."

Question:
The professor was of which subject?

 

Option 1: psychology
 

Option 2: biology
 

Option 3: chemistry
 

Option 4: physics

Correct Answer: psychology
 


Solution : The correct option is 1 i.e  "Psychology."
Explanation:

Let's examine the opening sentence of the passage:
- Once upon a time, a psychology professor walked around on a stage while teaching stress management principles to an auditorium filled with students.'
- It is clear from a thorough analysis of the aforementioned statement that the professor was a specialist in psychology. Therefore, the appropriate response is "psychology."

Correct Answer: abundance


Solution : The correct choice is the fourth option.

Explanation:

The sentence suggests that the Japanese way to alleviate stress, known as forest bathing, can be practiced in any location where trees are abundant, such as a nearby park.

The term abundance here implies a plentiful or large number of trees, creating a conducive environment for this stress-relief practice.

Therefore, the complete sentence would be: "You can forest-bathe wherever trees are abundance, including a nearby park".

Correct Answer: Reducing symptoms of stress and anxiety


Solution : One of the benefits of yoga as a therapy is reducing symptoms of stress and anxiety. Through physical postures, breathing exercises, and meditation, yoga can help individuals achieve a sense of calm and relaxation.

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