## Explain inertia of rest - definition, examples in daily life with pictures

### Explain inertia of rest - definition, examples in daily life with pictures Monday, 11 October 2021

'Inertia' this term is well known for those who take interest in physics. Inertia is a very important part of physics. But our question is from where this inertia came. So a quite simple answer would be from "Newton's laws of motion". So in this post we will not only discuss the types of inertia and their examples but also we will try to find out how inertia originated from Newton's law.

A famous person said that there are total 10% physics covered if you know Newton's laws. Here Newton's laws means not only three laws but all the portions including inertia, momentum, etc.

Now, let's focus on our main topic that is inertia of rest. So before we start the definition of Inertia. Let's understand what we have to know to understand full concept of inertia of rest.

So these are the things and terms related to inertia that everyone should know to clear the full concept of inertia of rest.

• What is inertia?
• Types of inertia?
• What is inertia of rest?
• Inertia of rest in terms of Newton's law.
• Deep discussion on inertia of rest.
• Property of inertia of rest.
• Factors depends on inertia of rest.
• One experiment to demonstrate inertia of rest.
• 8 most common examples of inertia of rest in our daily life.

## What is inertia?

We have studied in our previous classes that inertia is the tendency of a body to remain it in their original state. No matter whether the body is moving or stop.

In more simple way we can say that inertia is the legacy or identity of any object. Means that inertia indicates or tells about the nature of a body. But is that's it about inertia? Is there this limited information available about inertia?

We can't say anything because in our childhood we have just studied that much. So it's time to know more about inertia.

Apart from the types of inertia that we will discuss later in this post. Let's take a deep breath and lost on the deep analysis of inertia.

Everything in this universe is in two forms whether it may be in position of rest or in motion. Those bodies which are in a state of raised in this universe may because of some universal force or gravity. And those bodies which are in a state of motion may because of the some same universal force of gravity.

So how we can say that there has the body's tendency to remains at in state of rest or in state of motion. If something is in a state of rest may be because some force act on it. For example let's suppose a football is placed in playground. Now here two situation arises.

Situation No 1 :-

• The football on the ground is at in a state of rest may because no one applied an external force on it.

Situation No 2 :-

The football on the ground is at in state of rest may because of the flat surface with gravity pulling. If the ground will be incline it will start moving with gravity force.

No from the above discussion on two situation. We have understood that inertia of anybody it is not only sustainable with external force. But also unbalanced force.

Hence, in the definition of inertia we have to say that inertia is the tendency of a body to remains its state of rest or uniform motion until or unless no any external or unbalanced force applied on it.

Let's understand the concept of unbalanced force in Inertia.

As we have discussed above about two situation. The first is about no external force applied on the rest football. And the second is gravity. So here in this case of rest football on the ground. The gravitational force has cancelled by upward Normal force. Hence the resultant force will be zero. Therefore, the football has a tendency of rest called football has inertia.

### Types of Inertia

According to Newton's first law of motion. The inertia can be divided into three parts.

• Inertia of rest.
• Inertia of motion.
• Inertia of direction.

Today in this post we will only discuss about inertia of rest. Not only the definition but also the top 8 examples of inertia of rest that we have seen in our daily life.

All the scientific phenomenon whether it inertia, Newton's laws, thermodynamics laws, gravitation etc can be seen in our daily life style. We have to just open our scientific mind of seen.

As similar to other phenomenon that happen in our daily life. The one most common is inertia of rest. So before we discuss the examples of inertia of rest. Let's take an overview about what is inertia of rest?

## What is inertia of rest in simple words

Inertia of rest is simply defined as the tendency of any body to remains the original state of rest is called Inertia of rest.

In other words, if a body is in position of rest means it is not moving from one place to another then we can say that the body has a tendency to remains in state of rest.

### Inertia of rest in terms of Newton's law

The concept of inertia of rest, inertia of motion and inertia of direction comes from Newton's first law of motion.

According to Newton's first law of motion those bodies which are in state of rest remains in rest or in motion remains in motion until or unless no external or unbalanced force applied on it.

The definition is quite similar to the definition of inertia because the concept of Newton's first law and inertia is same.

Inertia is originated from Newton's first law. You can also say that inertia is the refined concept of Newton's first law.

## Deep discussion on Inertia of rest

Newton discovered three laws. Galileo was the first who talked about laws of motion and gravitation. But after the death of Galileo, it was Newton who published the three laws of motion called Newton's laws of motion. After the discovery of Newton's first law, the concept of inertia came.

Now, the question is why the concept of inertia came from Newton's first law. So the answer is hidden in the definition of Newton's first law.

As we know, Newton's first law says that any body which have a state of rest to remains in rest or which have a state of motion it also remains in motion. For example if a body is moving, it doesn't means some force is responsible for moving that body. It is the tendency of that body to keep moving forever until or unless no external or unbalanced force applied to it.

As we know the definition of inertia of rest is extracted from Newton's first law. Now, the meaning of inertia is also quite similar to the meaning of mass. That means if a body has some masses, then it has also some inertia.

So we can say that inertia is a type of force that can be experienced when the state of body changes. For example if we sit in a bus which is in rest. And if the bus suddenly start moving we will experience some backward force because of inertia of rest. Hence, we conclude that inertia is also a type of force.

### Property of inertia of rest

These are some properties that describe the inertia of rest.

• The first property of inertia of rest of a body is that it resist the change in their state of motion.
• The second property of inertia of rest of a body is that some forces are necessary to apply to move the rest body.
•  The last property is that when a body is at rest. It has a definite amount of inertia due to certain mass of the body.

### Factors depends on inertia of rest

There are two simple factors that the inertia of rest of a body depends.

1. The first factors that affect Inertia of rest is mass of a body. Means more the masses of a body. More will be inertia and less will be mass the less will be inertia.
2. The second factors that affect Inertia of rest is density of a body. More will be density the higher will be inertia and vice versa.

## One experiment to demonstrate inertia of rest

To perform this experiment take one glass, one square playing card and one 5 rupees coin.

Now, we have all the things that is necessary to perform the experiment of inertia of rest. We will perform this experiment in five simple steps. So let's start.

Step 1 :- Take one 5 rupees coin, one square size playing card and one glass.

Step 2 :- Now, placed this card on the above of the glass filled with water.

Step 3 :- After placing the card, let's place teh coin above the card.

Step 4 :- Pull the playing card suddenly in backward direction.

Step 5 :- After pulling it in inward direction the coin falls down vertically in the glass. This is because the original state of the coin was at rest. But after suddenly pulling the card. The card Start moving in backward direction. But card has a tendency to remains its state of rest. So it falls down vertically. This shows that the coin follows the concept of inertia of rest.

## 8 most common examples of inertia of rest in our daily life.

Here are the 8 examples of inertia of rest with explanation that we experiences in our day to day life.

1. Felling jerk after bus start moving.

This happens as follows, when we sat on a stop bus and if the bus start moving suddenly then we feel a background jerk in our body. This is due to the inertia of rest. Because the bus get motion but our body has the tendency to remains it in state of rest.

2. Coin drop vertically when the card flick.

Now, take a playing card, a coin and a glass of water. Put the card on the top of the glass and put coin on the card. Now, flick or pull the card in the backward direction. You will find that due to the suddenly pulling of the card, the coin drop into the glass filled with water.

This happen as follows When we put coin and card on the glass. All these things was in state of rest. But after the we have pulled the card, we applied a force only on the card not the coin placed above the card. So due to the tendency of the coin to remains in original state i.e, rest. The coin falls vertically into the glass.

3. Dust appear after shaking of dirty clothes.

You have must seen that when we beat the dirty clothes or blankets with sticks. Or even if we shake dirty clothes with our hands in sunlight. The dust particles appears to moving in surrounding of clothes. Have you ever be think, why this happens. So this happens because of inertia of rest of dust particles.

This happens as follows, when we start beating the dirty clothes. The the cloth start moving in to and fro motion but the dust particles remains in state of rest. So due to not moving of dust particles with cloth it seems like moving in surrounding.

4. Bullet makes a fine hole in glass

This example is very interesting. You have seen in many movies that when a person shoots a glass door with gun. The bullet of the gun makes a fine hole to the size of the bullet without breaking the glass.

This happens as follows : initially the glass of the window are in rest. But after the gun fired. The bullet strikes with the glass in a perticular are with respect to the size of the bullet. And dur to the very high speed of the bullet. The glass piece from that area where the bullet strikes goes with the bullet and makes a fine hole.

5. Glass not falls after table cloth removed.

Many magician performed this magic in different different show. You have must seen that magic.

Let's perform that magic. Take a glass of water. Placed it on the table with table cloth.

Now, pull the table clothes with high force. You will notice that the glass filled with water not drop. Even their water. So how this happens.

This happens as : when we suddenly pull the table clothes. The cloth get a motion and leave the tendency of rest. But the water glass was still in state of rest. Hence, due to the inertia of rest the glass not falls down after the cloth removed from the table.

6. Falling of fruits after shaking tree.

When we shake guava, or mango tree. The fruits fall down because the fruits wants to remains in state of rest.

7. Moved backward when train start from station.

When train start moving. The wheal of the train gets motion but the passenger has a tendency to remains in state of rest. Hence, it experienced a jerk in backward direction.

8. Shutter feels heavy during shop close.

If you noticed that when we pull the shutter to close the shop. The shutter feels quite heavy. This is due to the two reasons. First is due to their high mass and other is due to inertia of rest.

Before we apply a pulling force to the shop Shutter. The shutter is in state of rest. Even after applying force the shutter wants to remains at in state of rest. Hence, we feels heavy during shop close.