Newton's Laws of Motion: First, Second and Third Laws with Real-Life Examples

Laws of motion explain why objects move, stop, or change their direction. Whether it is a football being kicked, a bicycle speeding up, or a rocket launching into space, all these actions follow the same set of rules discovered by Sir Isaac Newton.

Have you ever noticed that passengers move forward when a bus stops suddenly? Or why you need to pedal harder to make a bicycle move faster? These everyday events can be explained with Newton's laws of motion. This article gives a detailed explanation of Newton's laws of motion, their formulas, examples, and applications in daily life.

Table of Contents

• What Are Laws of Motion
• Newton's First Law of Motion
• Newton's Second Law of Motion
• Newton's Third Law of Motion

What Are Laws of Motion

The laws of motion are three scientific rules that explain how objects move and how forces affect their motion. These laws were proposed by the English scientist Sir Isaac Newton in 1687 in his famous book Philosophiæ Naturalis Principia Mathematica, commonly called the Principia.

Before Newton's work, scientists could observe moving objects but could not fully explain why they moved in a particular way. Newton changed this by introducing three simple laws that connected force and motion. The three Newton's laws of motion are:

• Newton's First Law of Motion: Law of Inertia
• Newton's Second Law of Motion: Law of Acceleration
• Newton's Third Law of Motion: Law of Action and Reaction

Interestingly! These laws explain everything from a rolling ball and a moving bicycle to the motion of rockets and planets.

Even today, Newton's laws of motion are considered the foundation of classical mechanics and help scientists and engineers study and predict the motion of objects around us.

Newton's First Law of Motion

Newton's first law of motion states that,

"An object remains at rest or continues to move with the same speed in a straight line unless an external force acts on it."

This law is also called the law of inertia because it explains the tendency of objects to resist changes in their state of motion.

Let's first try to understand this with a simple example. A bicycle parked outside your house will remain in the same place until someone pushes it.

The fact is that every object tries to keep doing what it is already doing. If it is at rest, it wants to stay at rest. If it is moving, it wants to keep moving at the same speed and in the same direction.

Everyday Example of Newton's First Law

Have you ever noticed what happens when you quickly pull a tablecloth from under a plate? If the cloth is pulled smoothly and quickly, the plate remains almost in its original position.

This happens because the plate has inertia. It resists the change in its state of rest and tends to stay where it was.

Another example is a mango falling from a tree when the branch is shaken. The branch moves suddenly, but the mango tends to remain at rest due to inertia and eventually falls down.

These examples show that an object changes its state of motion only when an external force acts on it.

Newton's first law of motion forms the basis for studying force and helps us explain many events that happen around us every day.

Newton's Second Law of Motion

Newton's second law of motion states:

“The force acting on an object is equal to the product of its mass and acceleration.”

Mathematically, Newton's second law of motion is represented as,

F = ma

Where F is the force applied on the object (in newtons, N), m is the mass of the object (in kilograms, kg), and a is the acceleration produced (in metres per second squared, m/s²) 

This equation tells us two important things,

• If the force increases, the acceleration also increases.

• If the mass increases, the acceleration decreases for the same force.

For example, it is easier to push an empty suitcase than a fully packed one. The packed suitcase has more mass, so it needs more force to move with the same acceleration.

So, in simple words, the acceleration of an object depends on both the force applied and the mass of the object.

Everyday Examples of Newton's Second Law of Motion

Imagine pushing a shopping cart in a supermarket. An empty cart moves easily with a small push. But when the cart is filled with groceries, you have to push much harder to make it move at the same speed.

This happens because the loaded cart has more mass, so it needs a greater force to produce the same acceleration.

More Real-Life Examples

• A cyclist pedals harder to make the bicycle move faster.
• A gentle kick makes a football move slowly, while a strong kick sends it much farther.
• A small car speeds up faster than a heavily loaded truck when the same force is applied.
• An empty cardboard box is easier to push than a box filled with books.

These examples show that both force and mass decide how quickly an object's motion changes.

Newton's Third Law of Motion

Newton's third law of motion states,

"For every action, there is an equal and opposite reaction."

This means that forces always occur in pairs. Whenever one object exerts a force on another object, the second object exerts an equal force in the opposite direction.

Everyday Example of Newton's Third Law

Imagine standing in a small boat near the shore. When you jump forward onto the land, the boat moves backward.

How did it happen?

As you jump, your feet push the boat backward. This is the action force. At the same time, the boat pushes you forward with an equal force in the opposite direction. This is the reaction force.

This is why the boat moves backward while you move forward.

More Real-Life Examples

• While walking, your feet push the ground backward, and the ground pushes you forward.
• A swimmer pushes water backward and moves forward.
• A bird pushes air downward with its wings and rises upward.
• A rocket pushes hot gases downward and moves upward.

Connection with Momentum

Interestingly! Newton's third law of motion also explains the conservation of momentum. During any interaction, the total momentum of a system remains constant because the action and reaction forces are equal and opposite.

In this article, we have seen that the laws of motion explain how forces affect the movement of objects. We also studied Newton's first law of motion, what the second law of motion is, and Newton's third law of motion along with their formulas, examples, and applications. These laws help us explain many events that happen in our daily lives.