Newton’s three laws are the fundamental principles that explain many of the phenomena we encounter in our daily lives, and they form the basis of modern science and engineering, and still have a significant impact on relativity and quantum mechanics.
If you were to name the two people who have had the greatest influence on modern physics, even if you don’t know anything about physics, you’d probably name Isaac Newton and Albert Einstein. These two scientists fundamentally changed the paradigm of science through their innovative thinking and discoveries in their respective times. Isaac Newton laid the foundation for the physics that we do and continue to study today, and modern physics hasn’t moved on from his work. Newton combined experimental observation and mathematical analysis to develop physics into a rigorous discipline, and his laws are still valid for explaining many phenomena in the natural world. Many people mistakenly believe that Albert Einstein overturned Isaac Newton’s physics, but in fact Albert Einstein made Newtonian mechanics more complete with his own concept of space-time. Albert Einstein’s theory of relativity expanded our understanding of gravity and motion in particular, but it did not negate Newton’s classical mechanics, but rather integrated it into a larger framework. Because of this, Isaac Newton’s contributions still hold an important place in modern physics.
I’d like to introduce you to the three laws of Newtonian mechanics that Isaac Newton wrote that changed physics, in fact, changed the way scientists have looked at the world ever since. These three laws are more than just basic principles of physics; they help explain many of the phenomena we encounter in our daily lives and form the foundation of modern science and technology.
The first of the three laws of Newtonian mechanics is the law of inertia. It states that in the absence of an external force, an object will remain in motion. In other words, if an object is in motion, its direction of motion and magnitude will not change if no external force is applied. Also, when an object is not in motion, its direction of motion and magnitude do not change in the absence of an external force. In other words, the object stays at rest. This law allows us to explain many phenomena we experience in our daily lives. For example, when a car comes to a sharp stop, the body leans forward because of the law of inertia. Isaac Newton thought that only force could cause an object to move. An example of this is that when you dust a quilt, the quilt is pushed away, but the dust still falls. Or when you scoop up dirt and throw it, your hand stops in mid-strike, but the dirt still flies. The law of inertia is a basic principle that can be easily understood through everyday experience.
The second of the three laws is the law of acceleration. Better known as F=ma, this law states that an externally applied force changes the state of motion of an object. It states that acceleration is proportional to the force and inversely proportional to the mass. Here, m and a, or mass and acceleration, are measurable physical quantities, but F, or the amount of force, cannot be measured directly. Newtonian mechanics provides a way to calculate these forces. For example, if you push a car, it moves slowly if you push lightly, but faster if you apply more force. This law assumes that the mass of the object doesn’t change. If the mass of the object changes, you’ll need to use a different equation to calculate the force. For example, if the mass of a rocket decreases as it burns fuel, you’ll need to apply more complex laws of dynamics than the simple F=ma equation.
The final law is the law of action-reaction. If object A exerts a force on another object B, then object B exerts a force of equal magnitude and opposite direction on object A. Let’s look at a simple example. I hit a wall with my hand. Obviously, my hand hit the wall, but it feels painful as if the wall hit my hand. What shouldn’t be confusing about this law is that it’s not that A exerts a force on object B, and B exerts a force on A as a result, but that the two forces exist simultaneously from the beginning. This law plays an essential role in explaining many of the phenomena we experience.
For example, when a rocket is launched into space, the fuel burns in the rocket engine and the resulting gases are forcefully blown downward. The resulting force pushes the rocket upward, which is described by the law of action and reaction. The force (action) of the rocket blowing fuel downward acts as a force (reaction) to push the rocket upward. This is a phenomenon that cannot be explained without Newton’s law of action and reaction.
Newton’s three laws are essential to understanding and explaining not only physics, but also many phenomena in our everyday lives. His theories are not just theoretical concepts, but actually explain how the world we can observe works. For example, the laws of inertia and acceleration explain why, when a moving car comes to a sharp stop, the occupants are thrown forward. The reason a boat can float on water is also closely related to these three laws. The boat floats because the water pushes the boat up as the boat pushes the water down. This is an example of the law of action and reaction in action.
Newton’s laws are also important principles in many other fields of engineering, including mechanical engineering, aeronautical engineering, and architectural engineering. Newton’s laws allow us to design and build modern complex machines and structures. For example, when designing a skyscraper, the calculations for wind forces and the weight of the building are all based on Newton’s laws. As such, Newton’s laws play an integral role in science and engineering.
Although Newton’s physics was presented in the 17th century, its influence is still strong today. His theories were supplemented in the 20th century by Albert Einstein’s theory of relativity and the development of quantum mechanics, but Newton’s laws are still valid to explain most of the phenomena we encounter in our daily lives. As such, Newtonian physics has stood the test of time and remains the basic framework of modern science.
Another important significance of Newton’s physics is that he laid the foundation for the scientific method. By presenting a methodology that combined experimentation and mathematical analysis to explain natural phenomena, Newton laid the groundwork for science to develop in an objective and reproducible way. As a result, science gradually became an independent discipline, distinct from philosophy and theology.
In modern times, new theories have been proposed that go beyond Newton’s laws, but Newton’s work remains the foundation of science. For example, quantum mechanics and relativity deal with extreme situations where Newton’s laws do not apply, but on an everyday scale, they still apply. This shows how universal Newton’s laws are and how deeply ingrained his scientific contributions are.
In the end, Newton’s three laws are essential tools for understanding the world we live in. They don’t just stay in science textbooks; they play a key role in understanding the reality we experience every day. Newton’s physics is alive and well, and his laws remain an indispensable key to understanding our world.
