Newton's Law of Motion - Law of Motion

Newton’s Laws:- Newton’s Laws of Motion, formulated by Sir Isaac Newton in the 17th century, are foundational principles in physics that describe the relationship between the motion of an object and the forces acting on it. These laws provide a framework for understanding how objects move and interact, revolutionizing our grasp of the physical world. 

Newton's insights not only paved the way for classical mechanics but also laid the groundwork for many modern technological advancements. Go through the details of Newton's laws from the below article.

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What is Newton’s Laws?

Newton's Laws of Motion are three fundamental principles that form the foundation of classical mechanics. Formulated by Sir Isaac Newton in the 17th century, these laws describe the behaviour of objects in motion and the forces that act upon them. They revolutionised the way we understand the physical world, providing a comprehensive framework for predicting how objects will move under various conditions.

The First Law, known as the Law of Inertia, states that an object will remain at rest or move at a constant velocity unless acted upon by an external force. The Second Law establishes the relationship between an object's mass, the force applied to it, and its acceleration, expressed by the equation 𝐹=𝑚𝑎. The Third Law asserts that for every action, there is an equal and opposite reaction, emphasising the mutual interactions between objects.

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What are the Three Laws of Motion?

There are three Newtons Laws of Motion. Check out below for the details.

Newton’s First Laws of Motion: Law of Inertia

Newton’s First Law of Motion, also known as the Law of Inertia, explains how objects behave when there are no external forces acting on them. The term "Law of Inertia" highlights inertia, which is the tendency of objects to resist changes in their motion. This means that objects naturally stay at rest or keep moving at a constant speed in a straight line unless something causes them to change.

By calling it the Law of Inertia, Newton emphasised this natural tendency of objects. His first law states that objects will stay in their current state of motion unless an external force causes a change. Whether an object is stationary or moving steadily, it will continue to do so until a force, like a push or pull, acts on it.

Newton’s First Law reveals that an object will keep moving at a constant velocity if no net force is acting on it. If an object is in motion, it will continue moving at the same speed and direction. Similarly, if it is at rest, it will stay at rest. When an external force is applied, the object's velocity will change according to the strength and direction of the force.

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Newton’s Second Laws of Motion

Newton’s Second Law describes the relationship between the force applied to an object and the resulting acceleration. According to this law, the force acting on an object is equal to the product of its mass and acceleration.

Mathematically, Newton’s Second Law is expressed as:

F=ma

In this equation, FFF represents the force, mmm is the object's mass, and aaa is the acceleration produced. This law indicates that the acceleration of an object is directly proportional to the net force applied and occurs in the same direction as the force. It is also inversely proportional to the object's mass.

By understanding Newtons Laws, we can predict how much an object will accelerate when subjected to a given net force. The law highlights the intricate relationship between force, mass, and acceleration, providing a quantitative framework for analyzing the dynamics of moving objects.

In the context of the SI unit system, the proportionality constant kkk is equal to 1, simplifying the equation to its final form:

F=ma

Newton’s Third Laws of Motion

Newton’s Third Law of Motion states that for every action, there is an equal and opposite reaction. When two objects interact, they exert forces on each other that are equal in strength but opposite in direction. This means that forces always come in pairs.

To understand this concept, think of a book resting on a table. The book exerts a downward force on the table due to its weight. In response, the table exerts an upward force of equal magnitude on the book. This happens because the book slightly compresses the table's surface, causing the table to push back, similar to how a compressed spring releases its energy.

Newton’s Third Law also has important implications for momentum, which is a measure of an object's motion determined by its mass and velocity. The law states that in an isolated system, the total momentum remains constant before and after any interaction. This principle of momentum conservation means that the total momentum of the system does not change, regardless of the forces acting within it.

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Important Tips on Newtons Laws 

Newton’s First Law (Law of Inertia)

1. Car at Rest: A parked car will remain stationary until someone applies a force to move it, such as pushing or starting the engine.

2. Soccer Ball on the Field: A soccer ball will stay at rest on the field until a player kicks it. Once kicked, it will continue to move in a straight line at a constant speed until friction from the ground and air resistance slow it down.

Newton’s Second Law

1. Pushing a Shopping Cart: When you push an empty shopping cart, it accelerates quickly because the force you apply is greater relative to its small mass. If the cart is full, it requires more force to achieve the same acceleration due to its increased mass.

2. Rocket Launch: The engines of a rocket exert a large force to produce the necessary acceleration to lift off from the ground. The force is calculated by multiplying the mass of the rocket by the desired acceleration (F=maF = maF=ma).

Newton’s Third Law

1. Rowing a Boat: When you use oars to push water backwards, the boat moves forward. The force exerted on the water by the oars has an equal and opposite reaction force that pushes the boat in the opposite direction.

2. Jumping off a Diving Board: When you jump off a diving board, you push down on the board. In response, the board pushes you upwards with an equal and opposite force, propelling you into the air.

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Laws of Motion Numericals

1. Newton’s First Law (Law of Inertia)

Example: A hockey puck slides on ice with a constant velocity of 10 m/s. If no external forces act on it, what will be its velocity after 5 seconds?

Solution: According to Newton’s First Law, if no external forces act on the puck, it will continue to move at a constant velocity. Therefore, its velocity after 5 seconds will still be 10 m/s.

2. Newton’s Second Law

Example 1: A car with a mass of 1000 kg accelerates at a rate of 2 m/s². What is the net force applied to the car?

Solution: Use Newton’s Second Law formula F=maF = maF=ma: F=1000 kg×2 m/s2=2000 NF = 1000 \text{ kg} \times 2 \text{ m/s}^2 = 2000 \text{ N}F=1000 kg×2 m/s2=2000 N The net force applied to the car is 2000 Newtons.

Example 2: A force of 50 N is applied to a 5 kg object. What is its acceleration?

Solution: Use Newton’s Second Law formula a=Fma = \frac{F}{m}a=mF​: a=50 N5 kg=10 m/s2a = \frac{50 \text{ N}}{5 \text{ kg}} = 10 \text{ m/s}^2a=5 kg50 N​=10 m/s2 The acceleration of the object is 10 m/s².

3. Newton’s Third Law

Example: If you push a wall with a force of 30 N, what is the force the wall exerts on you?

Solution: According to Newton’s Third Law, the wall exerts an equal and opposite force on you. Therefore, the wall exerts a force of 30 N on you.

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Newton’s Laws FAQs

1. What are Newton’s Laws of Motion?

Ans. Newton’s Laws of Motion are three fundamental principles formulated by Sir Isaac Newton that describe the relationship between the motion of objects and the forces acting on them. They are:

• First Law (Law of Inertia): An object remains at rest or in uniform motion unless acted upon by an external force.

• Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (𝐹=𝑚𝑎).

• Third Law: For every action, there is an equal and opposite reaction.

2. How does the First Law of Motion apply to a car that suddenly stops?

Ans. When a car suddenly stops, passengers inside continue to move forward due to inertia. Without an external force, such as the seatbelt, they would not change their state of motion and could be thrown forward.

3. Why does a heavier object require more force to accelerate?

Ans. According to Newton’s Second Law, the acceleration of an object is inversely proportional to its mass. Therefore, a heavier object (greater mass) requires more force to achieve the same acceleration as a lighter object.

4. What is an example of Newton’s Third Law in everyday life?

Ans. When you jump off a diving board, you push down on the board with a certain force. The board exerts an equal and opposite force that pushes you upward into the air.

5. How does friction relate to Newton’s Laws?

Ans. Friction is a force that opposes the motion of objects. According to Newton’s First Law, friction acts as an external force that changes the state of motion of an object. It also affects the acceleration described by the Second Law by providing resistance.