Newton's three laws of motion


A basic definition of science is the study of nature and try to find different laws of nature. Well, Newton's law of motion is not an exception. As the name suggests Newton's laws gives us different rules that nature follows when something is in motion.

In simpler language, Newton's laws of motion helps us to find what laws and sets of rules nature follow when we or something is moving or about to move.

Pretty boring right ? Well, I thought the same, but you know that these laws have the same importance in science just like how important internet is to you.

For a brief description, Newton's laws of motion is divided into three main laws.

Newton's 3 law of motion:

1. Law of inertia.
2. Law of force and acceleration.
3. Newtons third law.

I understand it can be pretty boring to learn all the laws and to be honest it was for me as well when I was researching for this topic.

Don't worry ! I will try to explain these laws in an interesting way possible and try to make you understand what are these laws all about, including its importance in some of the things that wouldn't have existed if these laws were never found.

Newton's three laws of motion:

Well, learning Newton's all laws at once can be a bit confusing and instead of making things more confusing I will try to explain it in simpler words.

As I mentioned earlier, Newton's laws of motion is divided into three different laws so to have things simple, we will learn and try to understand the concept of each law one by one.

Law of inertia (1st law of motion): 

Newton's first law of motion also known as the law of inertia. Why? You will understand soon don't worry.

So before going ahead, let's see what first law of motion says

If I have to put it in a simple term, the law of inertia says that:

"If an object is at rest then it will continue to be at rest and if it's in motion it will continue to move in motion with the exact same speed unless and until no force is applied on it"

Well, this statement kinda looks contradictory when you see it with real-life experience because when something is moving and you left it as it is then after some time it will stop moving and you will need to apply force again.

Applying force to a car
This statement also seems fake because the way it looks from the first glance that if an object is in motion it will continue to move unless it doesn't get a stop. According to this logic, our cars and vehicle should move without a need for fuel. Once it will gain speed it should continue to move so but we all know, that's not the case.

If you don't apply a continuous force on the car it will stop. So does it mean that these all laws are meaningless and make no sense right ?

Well if you think that way, yes but I will also say that this law is correct, it's just many people get confused with the real meaning and concept of first law and later on they get confused. First law does say if an object is at rest it will continue to be at rest and if its motion it will continue to be in motion unless and until no force is applied on it.

So there is a condition that forces are needed to be applied to change the moving object from motion to rest or an object at rest from rest to motion.

And in the above example of a car, you are not considering all the forces of nature that are acting on a body. If you don't apply force to a moving car or vehicle it will eventually get stopped because an opposing force of friction is applied at the point of contact between car tires and road.

All natural forces on the car
This friction is the reason cars stop after some time because they apply a stopping force which is in the opposite direction of the car and due to this force, the car get stops if you don't apply a continuous force.

So this shows that the law is correct and in order to apply Newton's first law we need to consider all kinds of forces that are acting on a body.

To apply Newton's first law, instead of considering one force consider all the forces which are acting on an object.

Now as you know this law is also known as the law of inertia, but why ?

To understand that first, we should know the meaning of "inertia".

What does inertia mean ? 

Now, first I will tell you the scientific definition of inertia and then I will try to explain them in a simple way for better understanding.

Inertia means resistance created by any object whenever there is some change in its existing state.  `

It means that suppose there is an object which is in motion then it will tend to stay in it moving state only, same like defined in Newton's laws of motion and if you try to stop an object it will resist from stopping unless you don't apply enough force to stop.

Resistance means "to refuse to accept" 

This situation goes for when object is at rest. You may have noticed that in your day-to-day life. it's hard to move an object when they are at rest and you will need to apply more energy initially to make it move.

For example, if you want to move a computer desk from one to room to another, you will notice that you had to apply more force initially to make it move from that position. It's because the laws of nature. Computer desk was at rest and when you tried to move, it developed some resistance known as inertia.

Now I guess you are clear with why Newton's first law is also known as the law of inertia because one way or the other they both convey the same thing.

Law of force and acceleration (2nd law of motion):

I am not going to confuse you as the name suggest this law helps us in finding force formula and acceleration.

So as you can see, the first law of motion has shown how the force works on motion and second law finds the value of force.

So in some way they both are related and in the same way, the third law is also connected and together these three are known as Newton's laws of motion. 

As I had mentioned earlier that this law helps us to find the formula of force and acceleration but actually this law is the formula of acceleration and force. Confusing right ?

Don't worry I got your back!

So in simpler terms, the second law of motion states that:

Acceleration of an object depends on two factor: 1. The net force acting on a body 2. The mass of the body. 

But before going through about meaning of this statement, I am assuming that by this point you already know the meaning of "force" and therefore let me give you a brief description about "acceleration"

In terms of physics acceleration is the rate of change of velocity per unit time or if I have to put it into simpler words, its the amount by which the speed the object is changing its speed.

Now I hope you know what is the meaning of acceleration.

So if you look at the second law of motion, it's reasonable because we all know that heavier the object is the more energy you will need to move or accelerate it.

So the second law of motion concludes that the acceleration of the object depends on two factors:

1. The net force acting on a body: More the force, easier it is to move an object. Hence acceleration (a) directly proportion to (∝) to force (F) on a body.

a∝F
2. The mass of the body: More the mass, the harder it is to move an object. Hence mass (m) is inversely proportion (1/∝) to the acceleration (a).

Which will need more force to push?

a∝1/m

So from these two, we can actually conclude the final formula for acceleration which will be :

acceleration (a)=Force (F)/mass (m)

Now, this is the formula of acceleration and from this, we can also derive the formula of force (F).

Force(F) = Mass(m).Acceleration(a)

So now if you have any two values from this equation, you can easily find the third quantity.

Newtons 3rd law of motion:

I hope you now understand the first two laws of motion and with that in mind let's head towards the last and final law from Newton's laws of motion "The 3rd law of motion"

Well, this law doesn't have a name attached with it to remember it easily like the previous two but don't worry this is maybe the easiest law to remember or at least the easiest one from 3 laws.

The 3rd law states that:

Every action has equal and opposite reaction.

Well, this statement looks easy to remember and it actually is but understanding the concept can be a bit tricky. So we will start with the basics.

Whenever force is applied, between any two bodies or object there is a point of interaction between them. Now let's name both the bodies A and B respectively.

So whenever there is an interaction of force between two objects, both the bodies will apply some force on each other and according to this law:

If body A applies some force on body B then body B will also apply an equal but opposite amount of force on body A and thus, every action has an equal and opposite reaction.

I know you need an example to understand this more clearly so here it is.

Have you ever seen a rocket? just like Apollo 11 in which Neil Armstrong went to the moon. Well here is the clip for you:



In this clip, a rocket is actually applying force with his massive thrusters on the earth's surface and due to this as an opposite reaction to this action earth is also applying a force on the rocket in some way which allows him to explore the outer space.

This was not the only example of where Newton's laws of motion is applied.

Even in our day-to-day life from walking on the road to riding your favorite car. Even if you are typing or breathing everywhere there is some motion and these laws are applicable there as well.

Conclusion:

So these were the three laws of motion: 1. Law of inertia (to explain the concept of rest and motion in the real world) 2. Law of force and acceleration (to define force and acceleration)  3. Third law of motion. (ahhh ! just a law which is used everywhere wherever there is motion in nature)

So I hope I was able to clear your doubt and concept regarding Newton's laws of motion in this article. If you still have any query or doubt feel free to comment down below. It will be my pleasure to help you :)

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