# What is Newton’s First Law of Motion? (7+ Amazing examples)

Will this ball move?

Will this ball stop?

You might be thinking that it’s a simple question !!

Ball will move when someone kicks it, right?

Okay, But what about the moving ball, how will it stop?

Either you can stop it or with the help of friction, it will stop.

In the above line, what do you mean by kick?

It is nothing but an external force.

Similarly, what can you say about friction?

This is also one type of external force.

In short, External force is required to put a stationary body in motion or stop a moving body.

But, what happens when a boy is moving on a skateboard with uniform speed, still an external force is required to keep a skateboard moving?

Will this skateboard keep moving forever?

Now you know, it’s not that easy to answer this question.

In the 17th century, Issac Newton answered this question in a very simple way which is further known to us as Newton’s first law of motion.

Newton’s first law of motion states that:

“An object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it”

Do you know what is another name for Newton’s 1st law of motion?

Newton’s first law of motion is also known as the Law of inertia.

All the Newton’s three laws of motion together laid the foundation of classical mechanics.

Contents

## Understand newton’s first law with examples

“An object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it”

What do you understand by this statement?

Well, I know such statements are quite complicated to understand.

Don’t worry,

Check out some real life examples of newton’s first law of motion mentioned below.

You will surely understand the meaning of the whole statement of newton’s first law.

Okay, So let’s move on to the examples…

### #1 Bicycle ride

Both these boys are about to go for a ride along with their bicycles.

As you can see, both the boys (along with their bicycles) are initially at rest.

What do you mean by this?

It means that the object which is at rest remains at rest position only.

The object considered here is the bicycle. (You can consider either boy or bicycle as an object)

The bicycle will accelerate forward only when both the boys apply forces on it.

Now, when the bicycle comes in motion, see what happens…

As you can see, the bicycle moves forward when both the boys exerts force on it with their legs.

In short, the bicycle comes into motion when an external force is applied to it.

Now what happens?

Will both the bicycles keep moving forever?

You might be thinking, the bicycle will stop when the brakes are applied to it right?

Yes, you are right. But, what if there were no brakes?

See, the below image…

When one obstacle comes in between the road, the boy can’t control his bicycle. (As the speed of the bicycle is too high)

Now, here comes the first law,

When the bicycle strikes with the obstacle, it means that an external force acts on the bicycle.

(This external force is nothing but an unbalanced force only)

Only because of this unbalanced force, the bicycle stops.

Conclusion is,

Bicycle which is at rest remains at rest, and the bicycle which is in motion remains in motion. (Unless an unbalanced force acts on it)

### #2 Bowling

Newton’s first law of motion is clearly seen in the game of bowling.

Have you played this game?

If you have played, you already know how it works, right?

See this image…

As this boy holds the ball in the hand, the ball is initially in rest condition.

Now, tell me one thing… will this ball move on its own?

Obviously no, right.

The ball comes into motion when the boy throws it with his hand.

In short, the ball which is at rest remains at rest only.

As in the first half of newton first law of motion it is clearly mentioned that,

Object at rest remains at rest. (In this case, consider the ball as an object)

The ball comes in motion, only when an external force is given to it.

Now, what happens when the ball comes into motion?

You can see, the ball is moving towards the pin.

In short, the ball which is in motion remains in motion until it hits the pin.

See what happens when the ball hits the pin…

When the ball hits the pin, an external force acts on the ball.

Now, here comes the newton’s first law,

When the ball hits the pin, it means that an external force acts on the ball.

(This external force is nothing but an unbalanced force only)

Only because of this unbalanced force, the ball stops.

Conclusion is,

The ball which is at rest remains at rest, and the ball which is in motion remains in motion. (Unless an unbalanced force acts on it)

### #3 The Car

Do you know how Newton’s first law is applied while starting or stopping a car?

First of all, tell me, how will you state Newton’s first law of motion?

“An object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it”

Now, let’s understand the real life situation.

Imagine you are going somewhere in the car.

Now, the car does not start on its own, right?

See this,

As you can see, initially the car is in rest position.

Unless the boy starts the car, the car remains in rest position only.

In short, the car starts when an external force is given to it.

Now what when the car comes into motion?

Again the car which is in motion remains in motion only. (Unless an unbalanced force acts on it)

As the traffic signal turns to red, the boy applies the brakes and the car stops.

Again, here comes the newton’s first law,

When the boy applies the brakes, it means that external force is applied on the car.

(This external force is nothing but an unbalanced force only)

Only because of this unbalanced force, the car stops.

So the conclusion is,

The car which is at rest remains at rest, and the car which is in motion remains in motion. (Unless an unbalanced force acts on it)

### #4 Moving Scooter

In this example, I have clearly explained how Newton’s first law is applied while driving a scooter.

Let’s make it simple.

One boy is going to the market on his scooter.

As the scooter is initially in the rest position, it does not start on its own, right?

See this,

As seen above, here also…

Unless the boy starts the scooter, the scooter remains in rest position only.

Therefore, the scooter starts only when an external force is given to it.

In short, the scooter which is in rest remains in rest only. (If no external force is given to it)

Now when the scooter comes into motion, see what happens…

Now when the boy starts his scooter, the scooter and the boy both are in motion right?

(You can consider either boy or scooter as an object)

Now this scooter which is in motion, remains in motion only. (Unless an unbalanced force acts on it)

Now, when one obstacle (Stone) comes in between the road, see what happens…

As the stone comes in his way, the boy applies the brakes.

As his scooter’s speed is too high, he can’t control his scooter and falls down.

This shows the presence of newton’s first law,

When the boy applies the brakes, it means that external force is applied on the scooter.

(This external force is nothing but an unbalanced force only)

Only because of this unbalanced force, the scooter stops.

In short,

Scooter will not change its behavior unless an unbalanced force acts on it.

(Whether the scooter is in rest or in motion)

### #5 Ice Hockey

Here, I have explained the application of Newton’s first law with example of ice hockey. (You’ll definitely love it)

As the puck is initially in rest condition, it will remain in rest condition only.

Now, this puck will not move on its own, right?

Obviously No.

As you can see, the puck comes in motion when the player hits it with the hockey stick.

It means that an external force is given to it with the hockey stick.

(This external force is nothing but an unbalanced force only)

Again, this puck which is in motion remains in motion only. (until some another player hits it)

When the player hits the puck, unbalanced force acts on the puck.

Only because of this unbalanced force, the puck stops.

So the conclusion is,

The puck will not change its behavior, unless an unbalanced force acts on it.

(Puck which is at rest remains at rest, and the puck which is in motion remains in motion)

### #6 Tomato ketchup

When you ate pizza, last time?

There is no doubt that almost everyone has eaten pizzas.

Do you want tomato ketchup along with the pizza? (Well, I need it)

You know what,

Newton’s first law can be easily understood while applying the tomato ketchup on pizza.

You have definitely seen this example of Newton’s first law of motion.

Have you ever faced difficulty while removing tomato ketchup?

(Let me know in the comments, if you have experienced this)

The ketchup comes out easily when you hit the bottle from the back side.

In short, the ketchup comes out when an external force is given to the bottle.

(This external force is nothing but an unbalanced force only)

Only because of this unbalanced force, the ketchup comes out from the bottle.

Conclusion is,

The ketchup inside the bottle remains as it is, unless an unbalanced force acts from the back side.

(Which shows the presence of newton’s first law)

### #7 Pool

Have you played the pool?

Okay, that’s not important whether you have played or not.

But, do you know how Newton’s first law is applied while playing the pool?

See this…

As you know, the ball is initially at rest condition.

The ball comes in motion, when the girl hits the ball with the pool stick.

In short, the ball will remain in rest position only, if no external force is given to it.

Now, when the ball comes in motion see what happens…

Will this ball keep moving forever?

Obviously no, right. (As the friction reduces its speed)

The ball will only stop, when it strikes with another ball or with the edges of the table.

Conclusion is,

The only reason which puts a stationary ball in motion and stops a moving ball is the external force.

(This external force is nothing but an unbalanced force only)

Therefore,

The ball at rest remains at rest and the ball in motion remains in motion unless an unbalanced force acts on it.

If you want to read more examples on Newton’s first law of motion,

## Balanced and Unbalanced Forces

Till now, we have seen how the body changes its behaviour when an unbalanced force acts on it.

But, what happens if the forces are balanced?

Has this question come into your mind?

In this section, I’ll explain what happens when the forces are balanced.

But before that, you need to understand the basic definitions of balanced and unbalanced forces.

So let’s move on…

### What is balanced force?

If we see the definition of a balanced force, you might get confused.

“Those forces which are having same magnitudes and opposite directions are known as balanced forces

By reading the definition I didn’t know whether your concept of balanced force is cleared or not.

Let’s make it simple.

Have you played tug of war?

Don’t worry, if you have not played.

See the below example, (you’ll definitely love it)

#### Tug of war

Again I am saying, if you have not played this game, don’t worry.

From this example, you will surely understand the actual meaning of balanced force and how it works.

Now,

The forces are said to be balanced only if they are having same magnitudes and acting in opposite directions.

But do you know how it works in tug of war?

See this…

Here you can see, these two teams are preparing for a tug of war.

Who do you think will win? (Let me know in the comments below)

Any one team will end up pulling the rope on their side and wins.

Now by reading this example, you might be thinking that here there is nothing like a balanced force.

(Look at the figure mentioned below)

Here is the interesting part. (If you have noticed)

Both the teams are applying forces but not a single team is moving.

What do you think of this situation?

This condition is known as balanced condition. (Because of the balanced forces, not a single team is moving)

As both these forces are having the same magnitudes and forces are acting in the opposite directions.

In short, the motion of the body will not change if the forces are balanced.

(As the forces are balanced, none of those teams are moving)

### What is unbalanced force?

The definition of unbalanced force is so simple that by reading once you can remember it.

As seen above, the body will not change its behaviour if balanced forces are acting on it.

Here is the complete opposite definition for the unbalanced force.

In simple words, unbalanced forces can be defined as:

“The forces that cause a change in motion of a body are known as unbalanced forces

Let’s make it simple by considering one simple example of a box.

#### The box

Before understanding the unbalanced force, first revise the definition of balanced force.

Whatever forces, both the boys are applying on the box are balanced forces.

(As the forces are of equal magnitudes and having opposite directions)

In short, because of the balanced force, the box is not moving.

As it is clearly mentioned in newton first law of motion, the object will only accelerate if an unbalanced force acts on it.

Now what happens when both the boys push the box from the same side?

What do you think, the box will move?

See this…

As you can see, the box moves easily when both of them push from the same side.

Do you know the reason behind this?

This thing happens because of the unbalanced forces.

(As the directions of forces are same, the box changes its position)

So those forces that cause a change in motion of a body are known as unbalanced forces.

### Conclusion

If you have still not understood properly, just remember the two main points,

• If the forces are balanced, the body will not change its behaviour.
• If the forces are unbalanced, the body will change its behaviour.

Many students have misconceptions in their mind about the balanced forces and the action-reaction forces.

If you have the same misconception, You must clear your misconception.

## What if the forces are Balanced?

First of all, remember Newton’s first law of motion.

“An object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it”

Okay, that’s the first law of motion and also probably you have understood it well till now, right?

Now,

Let me ask you one simple question,

Is there any relation between the “external force” and the “unbalanced force”?

Remember what we have seen above,

Object at rest remains at rest and object in motion remains in motion.

(Until some kind of external force acts on it)

This external force is nothing but an unbalanced force only.

And the concept of unbalanced force is already discussed above.

(The object will change it’s behaviour only if an unbalanced force acts on it)

But, the question is…

What happens if the forces are balanced?

If the forces are balanced, the object will not move from its original position, right?

If you are confused,

Here is the simple flowchart that will easily make you remember, why objects don’t move when they are in a balanced condition.

If the object is at rest, its velocity is 0 m/s.

(So, the object remains in rest position only)

Similarly,

When the object is moving with uniform motion, its velocity is not equal to 0 m/s.

(As the object is in motion, its velocity can not be zero)

Therefore,

The object will continue to stay in uniform motion with the same speed and in the same direction.

And the statement of newton first law of motion gets proved.

(Object at rest remains at rest and object in motion remains in motion, unless an unbalanced force acts on it)

So now, I think both the concepts of balanced and unbalanced forces are clear to you, right?

If still, you have some doubts then read some examples given below.

### A man

Simply think you are standing on the floor.

Have you thought about the forces that are acting on you?

Are they balanced or unbalanced?

A man standing on the floor is in balanced condition.

As both these forces are having equal magnitudes and opposite directions, they are known as balanced forces.

Let’s take some other examples.

### A chair

Every day you are sitting on the chair, right?

But if you have noticed, the chair doesn’t break on its own, when you sit on the chair.

You know why the chair doesn’t break when you sit on it?

Because of the balanced force, the chair doesn’t break.

But how?

See this…

When you sit on the chair, the chair also applies an upward force on you.

As both the upward and downward forces are balanced, the chair doesn’t break.

(And both the forces are having same magnitudes and opposite directions)

So, only because of balanced force the chair doesn’t break.

### Dumbbells

Do you like to do exercise?

Everyday, this boy is doing different exercises with his dumbbells.

When he puts the dumbbell on the table, see what happens…

When the boy puts the dumbbell on the table, the table applies an upward force on the dumbbell.

As both the upward and downward forces are balanced, the table doesn’t break.

(And both the forces are having same magnitudes and opposite directions)

So, because of balanced force the table doesn’t break.

### The book

When the book is placed on the table, the table also applies an upward force on the book.

As both the upward and downward forces are balanced, the book is in balanced condition.

(And both the forces are having same magnitudes and opposite directions)

Now, when the girl lifts the table, (see what happens)

You don’t have to think in depth, it’s a simple thing.

When the girl lifts the table, both the upward and downward forces are not balanced.

Therefore, the book starts to slide after some tilt.

In short, because of an unbalanced force the book starts to slide.

Remember the definition,

“The forces that cause a change in motion of a body are known as unbalanced forces”

## Role of Inertia & Mass in Newton’s 1st law?

Object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it.

Newton’s 1st law of motion is also known as the Law of inertia. (You already know)

But, do you know why Newton’s first law is also called as the law of inertia?

And what is the importance of Inertia and Mass in Newton’s first law of motion?

In this section, I’ll explain why Newton’s 1st law of motion is also known as the law of inertia.

But before that, you need to first understand the definition of inertia.

### What is Inertia?

How will you define inertia?

Let’s make it simple.

Simply, Inertia can be defined as, tendency to do nothing.

(You can remember, Inertia as Inactiveness)

Let’s understand with one simple experiment of glass and coin.

#### Experiment (Try this at home)

To perform this simple experiment, you need one glass, coin & small card. (That’s it)

Place one coin on the card and put it on the glass.

Perform it now !! (It will be more clear to you)

Now, what happens if you hit the card with your finger?

The card gets thrown away, right?

The coin falls straight into the glass and the card gets thrown away.

(Only works, if you hit the card forcefully)

Now the question is, why not the coin gets thrown away along with the card?

See this,

The coin falls straight into the glass because of inertia.

(Remember the definition, Inertia is Inactiveness)

In short, the coin straight falls down into the glass, only because of inertia.

The coin remains as it is in its original position, Since no external force is given to it.

That’s the reason why newton’s first law is also known as the law of inertia.

Let’s see one more example of seat belt.

#### Seat belt

Newton’s law of inertia can be easily seen, while driving a car.

If you have noticed, seat belts stop you from moving forward when the brakes are applied.

Let’s make it simple.

Consider you are sitting inside the car.

Now when the brakes are applied, see what happens…

When the brakes are applied, the boy slightly moves forward.

Seat belt stops the boy from moving forward.

In short,

The boy will continue moving forward, if there were no Seat belts.

(Seat belt exerts an unbalanced force on the boy)

Remember the statement of newton’s first law,

“An object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it”

When the brakes are applied, the boy slightly comes forward.

Since the seat belt stops the boy. (Otherwise, the boy will continue moving forward)

### How mass depends upon Inertia?

Do you know how mass completely depends upon inertia?

From the below example you’ll definitely understand how mass completely depends upon Inertia.

Simply think, how will you hit the nail in the wooden block.

Obviously with a hammer, right?

Now I just want to ask you one simple question,

What happens when you place this wooden block on your hand?

You feel pain, right?

Now, just by placing some books on your hand, see what happens…

Because of the large mass of the book, the hammer blow is resisted by the books.

And you don’t feel the hammer blow.

(More the mass the object has, the more it will resist the change in its state of motion)

## Summary

It’s time to revise all the main points which we have seen till now in Newton’s first law of inertia.

• What is Newton’s first law of motion?

“An object at rest remains at rest and object in motion remains in motion unless an unbalanced force acts on it”

And you already know, what is another name for newton’s first law of motion, right?

Newton’s first law of motion is also known as the Law of inertia.

• What is balanced force?

“Those forces which are having same magnitudes and opposite directions are known as balanced forces

• What is unbalanced force?

“The forces that cause a change in motion of a body are known as unbalanced forces

• Conclusion

If the forces are balanced, the body will not change its behaviour.

If the forces are unbalanced, the body will change its behaviour.

• What happens if the forces are balanced?

When the object is at rest, the velocity is equal to 0 m/s. (Object remains in rest position only)

And,

When the object is moving with uniform motion, the velocity is not equal to 0 m/s.

(Object will continue to stay in uniform motion with the same speed and in the same direction)

• What is Inertia?

Simply, Inertia can be defined as, tendency to do nothing.

(You can remember, Inertia as Inactiveness)

• How mass depends upon inertia?

More the mass the object has, the more it will resist the change in its state of motion.

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Don’t you think, is easy to remember the statement of Newton’s first law of motion?

(Let me know by leaving a comment)