 # Newton’s Laws of Motion, Equations, Examples and FAQs.

Newton’s laws of motion are three fundamental principles formulated by Sir Isaac Newton in the late 17th century. Newton was the physicist who pioneer classical physics in his law of motion. These principles of motion describe the relationship between the motion of an object and the forces acting upon it.

# Newton’s Laws of Motion:

Newton’s laws of motion are three fundamental principles formulated by Sir Isaac Newton in the late 17th century. Newton was the physicist who pioneer classical physics in his law of motion. These principles of motion describe the relationship between the motion of an object and the forces acting upon it.

## Newton’s First Law of Motion (Law of Inertia):

The first law states that an object at rest tends to stay at rest, and an object in motion tends to stay in motion with a constant velocity unless acted upon by an external force. In simpler terms, objects have a natural tendency to resist changes in their state of motion. This property is called inertia.

Common examples to illustrate Newton’s First Law:

1. Sliding a book on a table: Suppose you have a book resting on a table. If you gently push the book, it will start moving with a certain velocity. However, if you remove all the external forces acting on the book, such as friction or air resistance, the book will eventually come to a stop and remain at rest. This is because, in the absence of external forces, the book follows Newton’s First Law and continues to move with a constant velocity until acted upon by another force.

2. A car abruptly stops: Consider a car moving at a constant speed on a straight road. When the driver suddenly applies the brakes, the car comes to a halt. However, the passengers in the car continue moving forward due to their inertia. This is why it is important to wear seat belts, as they provide an external force to prevent the passengers from continuing their motion. The passengers in the car exemplify Newton’s First Law as they tend to remain in motion unless acted upon by an external force (the seat belt).

3. Ice skating: Imagine a person ice skating on a smooth ice rink. When the skater pushes off the ice, they start moving in a particular direction with a certain speed. Once the skater is in motion, they will continue moving at a constant velocity until an external force, such as friction from the ice or the skater’s own actions, acts upon them. If the skater wants to stop, they have to exert an external force in the opposite direction to counteract their initial motion.

It’s important to note that Newton’s First Law applies to objects in inertial frames of reference, where no external forces are present. In non-inertial frames or when external forces act, the motion of objects may deviate from the law’s predictions.

In summary, Newton’s First Law of Motion states that objects at rest will stay at rest, and objects in motion will continue moving in a straight line with a constant velocity unless acted upon by an external force.

## Newton’s Second Law of Motion (Law of Acceleration):

The second law relates to this law and essentially states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Consequently, a larger force will cause a greater acceleration, while a larger mass will require a greater force to produce the same acceleration.

### The Equation of Newton’s Second Law:

The mathematical representation of Newton’s Second Law is:

F = ma

Where:

• F represents the net force applied to the object,
• m is the mass of the object, and
• a is the resulting acceleration of the object.

This equation states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. A larger force will result in a greater acceleration, while a larger mass will require a greater force to produce the same acceleration.

Few examples to illustrate Newton’s Second Law:

1. Example with a car: Suppose you are pushing a small car and a larger car with the same amount of force. According to Newton’s Second Law, the smaller car will experience greater acceleration than the larger car. This is because the smaller car has less mass, so the force produces a larger acceleration.

2. Example with a ball: If you kick a soccer ball and a bowling ball with the same force, the soccer ball will accelerate more than the bowling ball. This is because the soccer ball has less mass than the bowling ball. Newton’s Second Law states that a smaller mass will experience a greater acceleration for the same force applied.

3 Example with a rocket: When a rocket takes off, it experiences a powerful force called thrust. According to Newton’s Second Law, the force of the rocket’s engines (thrust) divided by the mass of the rocket determines its acceleration. By increasing the thrust or reducing the mass, the rocket’s acceleration can be increased.

In summary, Newton’s Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The formula F = ma quantifies this relationship, where F is the net force applied, m is the mass of the object, and a is the resulting acceleration.

## Newton’s Third Law of Motion (Law of Action-Reaction):

The third law states that for every action, there is an equal and opposite reaction. It means that when an object exerts a force on another object, the second object exerts a force of equal magnitude but in the opposite direction on the first object. In simpler terms, any force applied to an object will always have an equal and opposite force acting on the object exerting the initial force.

### The Equation of Newton’s Third Law of Motion:

The mathematical representation of Newton’s Third Law of Motion is:

F₁₂ = -F₂₁

Where: F₁₂ represents the force exerted by object 1 on object 2, F₂₁ represents the force exerted by object 2 on object 1.

This equation shows that the forces are equal in magnitude but opposite in direction. When object 1 exerts a force on object 2, object 2 simultaneously exerts an equal force in the opposite direction on object 1.

Common examples to illustrate Newton’s Third Law:

1. Example with a person pushing a wall: When a person pushes against a wall, they exert a force on the wall. According to Newton’s Third Law, the wall pushes back with an equal force in the opposite direction. Although the person applies a force to the wall, they don’t move because the reactive force of the wall balances the applied force.

2. Example with a bouncing ball: When a ball hits a wall or the ground, it exerts a force on the surface. According to Newton’s Third Law, the surface exerts an equal and opposite force on the ball, causing it to bounce back. The ball changes its direction due to the reactive force exerted by the surface.

3. Example with swimming: When a person swims, they push the water backwards with their arms and legs. As per Newton’s Third Law, the water exerts an equal and opposite force on the person, propelling them forward. The reaction force from the water allows the person to swim by pushing against it.

In summary, Newton’s Third Law of Motion states that every action has an equal and opposite reaction. The forces exerted by two interacting objects are equal in magnitude but opposite in direction. The equation F₁₂ = -F₂₁ represents this relationship, where F₁₂ is the force exerted by object 1 on object 2, and F₂₁ is the force exerted by object 2 on object 1.

## FAQs of Laws of Motion

1Q. What are Newton’s laws of motion?

A. Newton’s laws of motion are three fundamental principles describing objects’ behaviour in motion. They were formulated by Sir Isaac Newton in the late 17th century and are considered foundational principles of classical mechanics.

2Q.What is Newton’s First Law of Motion?

A. Newton’s First Law, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity unless acted upon by an external force.

3Q.What is Newton’s Second Law of Motion?

A. Newton’s Second Law states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. It can be mathematically expressed as F = ma, where F represents the net force applied, m is the mass of the object, and a is the acceleration produced.

4Q.What is Newton’s Third Law of Motion?

A. Newton’s Third Law states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on a second object, the second object exerts a force of equal magnitude but in the opposite direction on the first object.

5Q.Can you provide examples of Newton’s Second and Third Laws?

A.Certainly! An example of Newton’s Second Law is when you push a shopping cart with a greater force (net force), it accelerates more. An example of Newton’s Third Law is the recoil of a gun when fired—when the gunpowder explodes, it pushes the bullet forward with a force, and simultaneously the bullet pushes the gun backwards with an equal force.

6Q.Are Newton’s laws applicable to all objects?

A. Newton’s laws of motion are applicable to objects of various sizes, ranging from everyday objects to celestial bodies. However, at extremely small scales (quantum mechanics) or at speeds close to the speed of light (relativistic physics), these laws may not fully describe the behaviour of objects, and more specialized theories are required.

7Q.Are Newton’s laws still relevant today?

A. Yes, Newton’s laws of motion are still widely used in physics and engineering. They provide a solid foundation for understanding and predicting the motion of objects in most everyday situations. However, more advanced theories like Einstein’s theory of relativity or quantum mechanics are necessary for certain extreme conditions, such as those involving very high speeds or microscopic particles.

## Conclusion:

Newton’s laws of motion are three fundamental principles formulated by Sir Isaac Newton the physicist who pioneer classical physics in his law of motion. These laws of motion describe the relationship between the motion of an object and the forces acting upon it. The laws of motion formulated by Newton is observed in our daily life.