### Define Inertia of motion with 10 visual examples, formula and Application

Friday, 24 December 2021

Physics
After a long discussion on Inertia of rest. The time has come to talk about inertia of motion. Not only the definition but also 10 examples of inertia of motion that we have all experienced in our day to day life.

But before we go further, let's make a table of contents for this post.

__Topic covered in this lecture__

- What is an Inertia of motion?
- Formula of inertia of motion.

Q. What is inertia give an example of inertia of motion also explain which of the following has more inertia an empty box or a box full of books?

- Daily life examples of inertia of motion with visual picture.
- Application of inertia of motion.
- Where is Inertia of motion came from?
- Why inertia of motion related to Newton's first law of motion?

All the above topic are well explained in the following notes. So let's start.

## What is inertia of motion?

If we talk about only inertia, neither rest nor motion. Then it is a tendency of a body to keep their original state.

So, Inertia of motion is defined as the tendency of a body to keep their original state of motion forever. Untill or unless an external force is applied to it.

Please note that :- In inertia of motion, the direction of the moving object also constant. Means will be moving in only one direction forever.

Let's take an example to understand the inertia of motion more clearly.

__Case 1:-__Suppose a car is running on a straight road at a speed of 40 km/h. After 5 hours of constant moving, a curve turning has come. Now, if we didn't apply the external force (or brake) the car will be accident.

But if we apply the brake to the car, suddenly we feel a forward jerk. This jerk is because of inertia of motion.

This explains as follows : When we apply the brake the car has stopped but our body has a tendency to keep their original state of motion. Due to this we feel jerk in the forward direction.

__Case 2:-__Suppose the same car is running on a straight road at a speed of 40 km/h. After 3 hours of constant moving a road breaker has come.

Now, when the car cross the breaker, the wheel of the car leave the ground for some minor second and after that it again touches the ground. But due to this we felt a jump inside the car.

This jump is because of inertia of motion. This explains as follows:

While the constant moving of the car. Our body is in state of rest with respect to other person inside the car. But in motion with respect to the people who has seen from outside the car.

Please note that :- This case is also a good example of rest and motion are relative terms.

So, after crossing the road breaker our body gain some motion but after some micro second it again touches the ground. So we felt jump in upward direction.

__Case 3:-__Suppose, we are sitting in the same car. After some time, if we change the direction of the car. We felt down in the right side because of the inertia of direction.

### Rest and motion are relative terms.

Suppose a person is standing on the moon. We can say that person is in state of rest with respect to another person stand beside them. But in motion with respect to that person who seen both of them from earth.

Let's take another example to illustrate our above example.

Suppose we are sitting on a running train. Here we can say that we are in state of rest with respect to other passages sitting besides us. But we are still in motion with respect to the passages standing on the platform.

### formula of inertia of motion

Please note that there is no definite formula to calculate the inertia of motion, rest or direction.

Inertia is a phenomenon in science. It is not a mathematical concepts or equations.

The inertia of momentum has a formula. But not inertia of motion.

Inertia of motion is used to understand the concept of the questions. Inertia can be used to clean the concept of Newton's first law of motion.

### Q. What is inertia give an example of inertia of motion also explain which of the following has more inertia an empty box or a box full of books?

In most simple words, Inertia is the tendency or behaviour of a body that helps them to keep their original state unless or until an external force is applied to it.

Please not that the body may be in state of rest or motion.

**Example of inertia of motion.**

Applying brake suddenly when the car is in motion. This explains as follows:

When the car is moving in a straight line at constant speed. And if we apply the brake, it goes slow down and Stop after some time. Due to the inertia of motion. Because the moving car always wants to remains in motion as according to Newton's first law. But when we apply brake, Newton's law break. That's the reason we feel forward force after applying brake.

Now, the question is which has more inertia.

1. An empty box.

2. A box with full of books.

Hence, to answer this question. Let's first understand that the object which has more masses has more inertia than the lighter one.

So, here the box full of books has more inertia than the empty box.

## Daily life examples of inertia of motion with visual picture

- Feel backward force when car suddenly start.
- Feel forward force when car suddenly stops.
- Collision of moving objects in space.
- Moving of satellite in space.
- Moving of planets in space.
- Jump from moving train.
- Objects come to you when throw inside the moving train.
- Athletes not stop running even after reach to the final position.
- The moving of bike for some time, even we off the engine.
- Continuous moving of stone attached with thread in circular path.

These are the 10 most common and familiar examples of inertia of motion that we have expressed in our life.

## Application of inertia of motion

- Application of car brakes, train brakes etc works on the inertia of motion.

- The runner athelete also uses the application of inertia of motion for long jumping.

- The scientist also uses the application of inertia of motion in space satellite.

- The study of the motion of earth and other planets can be understood by the application inertia of motion.

- Aeroplane take off and landing is also use application of inertia of motion.

### Why inertia of motion related to Newton's first law

According to Newton's first law of motion, a rest body always remains in state of rest and a moving object always in state of motion.

Hence, inertia of motion said that, a body which is moving with some velocity. It always moving forever until or unless an external force is applied to it.

So, the definition of both the term are inter relative. Not only the definition but also the concept of both the terms are co-related.