Newton’s 3 Laws of Motion

What Are Newton’s 3 Laws?

Newton proposed three laws of motion that explain interactions between solid objects, describing force, inertia, and reaction forces.

Newton’s three laws of motion were the first quantitative and predictive laws of mechanics. For over two hundred years, physicists were unable to produce any experiment that invalidated any one of these laws, and even today they function as close approximations for the vast majority of real-world problems, which is why engineers still use them for calculations.

Introduction to Newton’s 3 Laws of Motion

Isaac Newton’s 3 Laws of Motion are fundamental principles that explain the behavior of objects in motion. Understanding these laws is essential for comprehending the basic principles of physics and engineering.

  1. The first law of motion, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity unless acted upon by an external force. This means that the natural state of an object is to maintain its current state of motion or lack thereof. In other words, objects have a tendency to resist changes in their state of motion.
  2. The second law of motion describes the relationship between the force applied to an object, its mass, and its acceleration. It states that the acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. This means that the greater the force applied to an object, the greater its acceleration will be, and the greater its mass, the smaller its acceleration will be.
  3. The third law of motion is commonly known as the law of action and reaction. It states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object exerts an equal and opposite force on the first object. These forces are always present in pairs and act on different objects.

First Law of Motion: Mass & Inertia

Newton’s First Law, also known as the Law of Inertia, is a fundamental principle in physics. It states that an object at rest will remain at rest, and an object in motion will continue to move in a straight line at a constant velocity unless acted upon by an external force.

Objects at rest tend to stay at rest and that objects that are in motion tend to stay in motion

One common misconception is that the first law only applies to objects at rest. In reality, the first law applies to any object in motion or at rest, stating that an object will remain in its state of motion unless acted upon by an external force.

This law, while not validated by everyday experience, was easy to predict by adding friction to virtually every calculation of motion. This law was also the first mention in the history of the idea of frames of reference in which laws were valid, a concept that would later become the basis for the theory of relativity.

Understanding Newton’s First Law is important because it helps us understand why objects behave the way they do. It also helps us design and build things that move the way we want them to. For example, engineers use this law to design cars that can brake and accelerate safely, airplanes that can take off and land smoothly, and even roller coasters that provide a thrilling ride without endangering passengers.

The Second Law: Force, Mass & Acceleration

Newton’s Second Law of Motion states that the acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. In simpler terms, the heavier the object, the more force it will take to move it, and the more force applied to an object, the faster it will accelerate.

Any force applied to a body produces acceleration and that the product of the acceleration and the mass of the object is the force applied

Another common misconception is that the second law applies only to objects that are accelerating. The second law actually states that the force acting on an object is proportional to the object’s mass and the acceleration it experiences. This means that the second law applies to any object, whether it is accelerating or not.

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Understanding Newton’s Second Law is crucial in many areas, such as engineering, physics, and sports. For instance, in sports like baseball or golf, the amount of force applied to the ball determines the distance it will travel. Thus, by applying a greater force, you can make the ball travel farther.

Third Law: Action & Reaction

Newton’s Third Law is commonly known as the Law of Action and Reaction. This law states that for every action, there is an equal and opposite reaction. This means that if an object pushes or pulls on another object, the second object will push or pull back with the same force but in the opposite direction.

For every action there is an equal and opposite reaction

As a result of this law, we get the fact that energy is always conserved in mechanical systems. Although this means that in every exertion of force, the magnitudes of the forces are equal, the accelerations need not be so. If a massive object strikes a small object, then the small object will accelerate a lot faster than the large one.

Newton's Third Law of Motion: Action Reaction Pairs - StickMan Physics
Newton’s Third Law of Motion: Action Reaction Pairs – StickMan Physics

Some people believe that the third law states that every action has an equal and opposite reaction and that these forces cancel each other out. While it is true that the forces are equal and opposite, they do not cancel each other out. Instead, they act on two different objects and can have different effects.

An object’s mass is a constant inherent property that measures the amount of matter. An object’s mass is related to its inertia and gravitational force.

Real-world examples of Newton’s 3 Laws

Now that we have a basic understanding of the three laws of motion, let’s take a look at some real-world examples of how they apply to everyday life.

First, let’s take a look at the first law. Imagine you’re in a car traveling at a high speed and suddenly the car comes to a stop. You’ll feel a sudden jerk forward because of the inertia of your body. Similarly, when you’re on a rollercoaster, you feel pushed back when the coaster suddenly stops.

Next, let’s consider the second law. A great example of this law can be seen when you’re playing a game of pool. You use a cue stick to hit the ball, and the ball then goes in the direction you aimed it towards. The force you applied to the ball with the stick caused it to move in the direction you wanted it to.

Finally, let’s look at the third law. A good example of this law can be seen when you’re walking. When you take a step, you push the ground backward with your foot, and the ground pushes back with the same amount of force, causing you to move forward.

Newton’s Laws of Motion and Motion in Space

Understanding Newton’s Laws of Motion is essential to understanding motion in space. The three laws form the basis of classical mechanics and are fundamental to our understanding of how objects move both on Earth and in space.

The first law states that an object at rest will remain at rest, and an object in motion will remain in motion, at a constant velocity unless acted upon by an external force. This law explains why an object in space will continue to move with the same velocity and direction unless a force acts upon it.

The second law states that the acceleration of an object is directly proportional to the force acting on it and inversely proportional to its mass. This law explains how rockets can accelerate in space by expelling fuel in the opposite direction of the desired motion.
The third law states that for every action, there is an equal and opposite reaction. This law explains why rockets can be propelled forward in space by expelling fuel in the opposite direction.

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History and Relevance

Newton proposed the first two laws in a paper titled Principia Mathematica, and the third shortly thereafter. When combined with the universal law of gravitation and the invention of calculus, Newton’s laws were the first laws that provided a complete explanation for universal phenomena, which lasted over two hundred years until the discovery of light speed and relativistic mechanics.

Importance of understanding Newton’s Laws of Motion in everyday life

Understanding Newton’s Laws of Motion can be very beneficial in our everyday life. Although the laws were first formulated in the 17th century, they are still relevant today and can help us understand the world around us.

For example, the first law states that an object at rest will stay at rest, and an object in motion will stay in motion unless acted upon by an external force. This means that if you are in a car and it suddenly comes to a stop, you will continue moving forward at the same speed until the seatbelt or airbag stops you. Understanding this law can help us take necessary safety precautions while driving.

The second law states that force equals mass times acceleration. This law can be applied in many areas of our life. For example, if you are trying to move a heavy object, you will need to apply more force to accelerate it. Similarly, if you are trying to lose weight, you will need to decrease your mass or increase your acceleration to see results.

The third law states that for every action, there is an equal and opposite reaction. This law can be seen in action when we walk, swim, or ride a bike. Understanding this law can help us improve our performance in these activities and avoid injury.

Applications of Newton’s Laws of Motion in Engineering and Technology

Newton’s Laws of Motion have a great impact on the field of engineering and technology. These laws are applied to many engineering and technological innovations that we use in our daily lives without even realizing it.

The first law of motion, also known as the law of inertia, is applied in seat belts and airbags. The seat belt is designed to keep the person seated in the car in case of a sudden stop, and the airbag is designed to reduce the impact of the collision on the body.

The second law of motion, which explains the relationship between force, mass, and acceleration, is used in the design of airplanes, rockets, and cars. Engineers use this law to calculate the amount of force required to move a certain mass at a certain acceleration.

The third law of motion, which states that for every action there is an equal and opposite reaction, is used in the design of many machines, including engines and turbines. These machines work by creating a force that is equal and opposite to the force applied to them.

In addition to these practical applications, Newton’s Laws of Motion are also used in the development of computer simulations and models. Engineers and scientists use these simulations to design and test new products and innovations before they are actually built.

Significance of Newton’s Laws of Motion

Understanding Newton’s three laws of motion is essential for comprehending the fundamental principles of physics. These laws describe how objects will behave when acted upon by external forces, and they are the foundation for many scientific principles and technological advancements we rely on today.

These laws have significant real-world applications in countless fields, from engineering and transportation to sports and entertainment. The principles of Newton’s laws can be seen in everything from the motion of a rocket ship to the acceleration of a ball when it is thrown.

We hope you enjoyed our beginner’s guide to understanding Newton’s 3 Laws of Motion! These laws of physics can be intimidating at first, but once you grasp the basics, they become much more accessible. Knowing these laws can help you understand how objects move and interact with each other, which is important in many areas of life, from engineering to sports. We encourage you to continue learning and exploring the fascinating world of physics, and don’t hesitate to reach out if you have any further questions!

Further Reading

Scheck, Florian. From Newton’s Laws to Deterministic Chaos, Springer, 2009.

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