[Physics Class Notes] on Fluid Pdf for Exam

Do you ever wonder why some substances flow? And why do some substances flow differently from others? Do only liquids flow? What are these substances? Answers to all of these questions will be answered today. All these phenomena are associated with fluids.

The scientific fluid definition is very simple to understand. Fluid meaning refers to a substance that does not have a definite shape and yields easily to external pressure. It can be a liquid or a gas. We say that a fluid can flow easily and we find its applications more in clutch or coupling, where fluid helps transmit the power supply.

Fluid Examples in Everyday Life

You might have heard of the word ‘Fluid’; now, we will look at some examples of everyday use of this term to understand it better.

• The patient is severely dehydrated, and he needs fluids urgently.

• The tanks on the rooftop are placed for storing fluids like oil, kerosene, and gas.

• We generally keep our household cleaning fluids out of the reach of the children.

• Our stomach collects gastric fluids around its edge to digest food.

• We saw some kind of fluid oozing (a viscous liquid) coming out from the trunk of the tree.

Fluid Definition in Physics

In Physics, the fluid definition is:

A fluid is a substance that continually flows or deforms when we subject it to shear stress or external force. 

The fluid is one of the phases of matter and we consider fluids like liquids, gases, and plasmas. One of the scientific definitions of fluid is that these are substances with zero shear modulus, or, in simpler words, these substances cannot resist the shear force applied to them.

Fluid Information Definition

To understand fluid information definition, let’s consider the below one-line statements:

The term ‘fluid’ is more closely related to being a solid plasma; however, we consider it as liquid and gas. A fluid carries no shear modulus. Now, let’s understand the types of fluid flow:

Fluid flow has of the following types:

1. Steady or unsteady

2. Compressible or incompressible

3. Viscous or non-viscous, and 

4. Rotational or irrotational.

Steady or Unsteady Flow

The flow of fluid can either be steady or unsteady, depending on the velocity of the fluid:

• Steady: In steady fluid flow, the fluid’s density remains constant at every point.

• Unsteady: During the unsteady flow, the fluid’s velocity differs between any two points.

Viscous or Non-Viscous Flow

Liquid flow can be vicious or non-viscous.

The resistance offered by a fluid to flow is known as viscosity. A fluid that offers high resistance to flowing is known as a viscous fluid and its flow is said to be vicious.

On the contrary, a fluid that flows relatively freely is said to have low viscosity or is known as a non-viscous fluid and its flow is said to be non-viscous. 

 

Viscosity is a measure of the thickness of a fluid, and very sticky fluids viz: motor oil or shampoo are called viscous fluids.

Fluid Characteristics

We see ‘fluid definition’ a lot many times; however, ‘fluid’ is used in everyday life and is understood with some of its characteristics.

Now, let’s look at some characteristics of a fluid:

1. Capable of flowing and easily changing its shape.

2. Constantly changing or apt to variations.

3. Smooth in movement, i.e., easy flow.

Types of Fluids

Now, let’s look at types of fluid.

The Types of Fluids are:

1. Ideal Fluid: An ideal fluid is incompressible and it is an imaginary fluid that doesn’t exist in reality. Also, it doesn’t have viscosity. In the real world, ideal fluid does not exist.

2. Ideal plastic Fluid: When the shear stress becomes proportional to the velocity gradient and more than the yield value, the fluid is said to be the ideal plastic fluid. E.g., Water suspension of clay and fly ash 

3. Real Fluid: Fluids having viscosity are real fluids. E.g., petrol

4. Newtonian Fluid: A fluid obeying Newton’s law of viscosity is known as a Newtonian fluid. E.g., glycerol thin motor oil.

5. Non-Newtonian Fluid: A fluid not obeying Newton’s law of viscosity is said to be a Non-Newtonian fluid. E.g., cornflour and water

6. Incompressible Fluid: When the density of the fluid remains invariant with the application of external force, it is said to be an incompressible fluid. E.g., The stream of water flowing at high speed from a garden hose pipe

7. Compressible Fluid: When the density of the fluid varies with the application of external force, it is a compressible fluid. E.g., gas, steam, etc.

Interesting Facts About Fluids

A very common fact about fluids is that they have a constant volume, meaning that they are confined within the vessel they are kept in.

Now, let’s look at a few more interesting facts about fluids.

1. After cooling liquids, we can compress them, except for ice, which expands.

2. We cannot compress water.

3. Water has three forms – solid, liquid, and gas(vapor)

4. The liquid form of fluid is a prerequisite of carbon-based life

5. Most of the water present on the earth is from outer space.

• Cats release a lot of fluid in the saliva.

• Fluid mechanics is the study of the forces on the fluid and how fluids move. Fluid mechanics can be divided into parts: fluid statics and fluid dynamics. Fluid statics is the study of fluids at rest, and fluid dynamics is the study of fluids in motion. 

• Fluid mechanics is a branch of continuum mechanics, a subject that models matter without using the information of what atoms they are made of.

Why study Fluid from ?

Fluid is an extremely important topic in Physics. An entire branch is dedicated to its study. Here has tried to cover the topic for you as holistically as possible. After going through this, you will gain enough theoretical understanding of the topic to tackle questions based on basics. It will also facilitate you to understand the advanced level concepts. Going through it thoroughly will not only help you fetch marks in the upcoming exams but also in other future exams which may include this topic. 

Conclusion

This section has discussed the topic of Fluid for you in brief. The aim was to cover the fundamentals of the topic. Here we have covered standard definitions, characteristics, types, examples, and fun facts about the fluid and related phenomenon. All the content made available to you is of the utmost quality. To fuel your curiosity further, has also added a few fun facts in the last part of the topic. You should go ahead and make the best use of this content and many other materials made available to you by .