 Newton's three Laws of Motion - Future Study Point # Newton’s three Laws of Motion # Newton’s three Laws of Motion The Three Laws of Motion was discovered by Newton,so these laws are also called Newton’s three laws of motion. The discovery of these laws of motion led Newton to be called as the father of mechanics a branch of physics. Newton first discovered the universal force of gravity which was succeeded by the discovery of three laws of motion. Three laws of motion are part of the physics book of middle and higher secondary school. Here each law of Newton is explained beautifully by an experienced physics teacher.

Newton’s first law of motion reveals the concept of inertia, inertia is the physical property of the matter which opposes a change in its original state, the uniform motion of the moon around the earth is its example. The second law of motion states that acceleration on an object due to a constant force is inversely proportional to the mass of the object, its example is the moon and the earth both are attracting each other by the same force but the moon is revolving around the earth. Newton’s third law of motion states that every action has an equal and opposite reaction, an example is the propulsion of the rocket to the space, the rocket contains a number of chemicals in its fuel chamber that results in the release of the gas from its back portion forcefully, this force generates another force of the same magnitude towards the sky, this is how rocket goes up to the space.

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## Newton’s three laws of motion

Table of content

• The first law of motion
•  Inertia
• Application of first law of motion
• The second law of motion
• Application of second law of motion
• Third law of motion
• Application of third law of motion
• Conservation of momentum
• FAQs about Newton’s three laws of the motion

## Newton’s three Laws of Motion

### First Law of Motion:

The whole of the universe is controlled by certain balance forces on a basis of macroscopically and microscopically. All the objects in the universe are placed in their unique position, it is that we can say that universe is arranged in a matrix. All heavenly bodies are bounded by a certain balance gravitational force and all the particles in a matter are also bounded by the balance of intermolecular and nuclear forces. The position of these objects in the universe can’t be changed until an external force is applied to them so Newton’s first law of motion is stated as follows.

An object remains in its own position until an external force is applied to it.

If a car is moving at a uniform speed, It will continue to move at the same speed as long as no external force (i.e. stop or accelerator) is applied to it.

An object remains in a stationary position until an external force is applied to it.

According to the first law of motion, a body remains in its own position until an external force is applied to it, it is caused due to the mass which resists a change in the state of the body. The first law of motion gave birth to the concept of inertia, the inertia is the physical property of all objects. Inertia is the tendency of an object to resist a change in itself. It is proportional to the mass of an object.

Application of inertia: The head of the passenger is stuck to the front seat when the driver applies a sudden break. It happened because the seat of the passenger is struck on the floor of the bus so as soon as the bus stops the seat of the bus and lower part of the passenger’s body also stops but his upper part because of less mass (i.e less inertia) still carried on to move resulting his head struck to front seat.

When the trunk of a tree is shaken the leaves fall on the ground because the trunk regains its position faster due to high inertia but leaves still carried on in motion due to lesser inertia, therefore an imbalance of outward force exerted on the leaves that detached the leaves from the surface of the tree and fall on the ground.

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### Second Law of Motion: Newton discovered the second law of motion, as it is evident from the first law that if the mass of an object is more, its inertia will be more so the larger force is needed to displace a havier thing than the lighter thing. In displacing the heavier object to a particular point more time is required than displacing the lighter object to the same point. So another physical quantity momentum(P) was discovered by the newton, momentum is the product of mass and velocity. Newton observed that the force applied to an object while displacing it from one place to another is directly proportional to the rate of change of momentum.

Let the mass of an object is m, the initial object is u, the final velocity is v, and the time taken in achieving velocity v is t.

From the first equation of motion we have

Where a is the acceleration produced by the applied force

Substituting the value of a in above equation

F = kma

Where k is the constant  of proportionality

Let m = 1kg, F= 1N and k = 1m/s²

k = 1Nkg-1m-1

Putting this value in F = kma

F = ma

So, from this equation, we can also explain Newton’s second law of motion that if the same constant force is applied on two objects then the lighter object will be accelerated more compared to the heavier object.

Newton’s second law of motion states that acceleration is inversely proportional to the mass.

Application of the second law of motion: If the applied force is constant then the light object is accelerated more compared to a heavy object.

### Third Law of Motion:

Newton observed that every action has an equal and opposite reaction which is known as Newton’s third law of motion.

Application of the third law of motion: If we throw a ball by a certain force toward a wall then the wall also strikes the ball with the same amount of force.

The great application of Newton’s third law of motion is the invention of the rocket. In the rocket, many types of chemicals are used, under a high temperature and pressure combustion of these chemical produces hot gases, these gases ejects from the nozzle of the rocket with a very high velocity. The escaping of gases provides the rocket with an equal amount of upward thrust that moves the rocket in the upward direction towards the sky. ### Verification of conservation of momentum with the help of Newton’s third law of motion:

Let object A of mass apply a force    on object B of  mass then object B will also apply an equal opposite force on object A,

Force is directly proportional to the rate of change of momentum.

According to the third law of motion

Where    and are the initial velocity of both objects and and are the final velocity of both the objects .

The initial momentum of both objects = Final momentum of both objects

### FAQs about Newton’s three laws of the motion

Q1. What is Newton’s first law of motion?

Ans. Newton’s first law of motion states that the state of an object is not changed until and unless an external force is applied to it.

Q2.What is the second law of the motion ?

Ans. The second law of motion states that the mass of an object is inversely proportional to the mass.

Q3.What is the third law of the motion?

Ans. The third law of the motion states that every action has an equal and opposite reaction.

Q4. What is the application of the first law of motion?

Ans. The application of first law of motion is the inertia.

Q5.What is the application of the second law of motion?

Ans. According to the universal law of the gravitational force, the sun and the earth attract each other by the same gravitational force but it is the earth because of lesser mass accelerates with respect to the sun and thus revolves around the sun.

Q5.What is the application of the third law of motion?

Ans. If we throw a ball to the surface of a wall then the wall also bounces back the ball with the same force in opposite direction.

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