This means that all bodies tend to remain in the state they are initially in, that is, if they are in motion, they will tend to remain in motion until someone or something stops them; if they are immobile, they will tend to remain immobile until someone or something breaks their state and makes them move.
In our days, this statement may seem rather obvious, but it should not be forgotten that this discovery, as well as other very relevant ones, among which we can mention the law of universal gravitation and studies on the decomposition of white light into different colors, Isaac Newton did approximately 450 years ago.
Newton’s Laws, which include this Law of Inertia, in addition to the Law of Interaction and Force, and the Law of Action and Reaction – and which together form Newton’s laws of Dynamics – came to scientifically explain how objects or bodies with mass act and they react to the presence or absence of forces exerted on them.
10 Examples of the Law of Inertia
1- The car that brakes abruptly
The most graphic and everyday example that explains this law is the movement our body makes when we drive a car at a constant speed and it stops abruptly.
Immediately the body tends to continue in the direction the car was carrying, so it is thrown forward. This movement will be smooth if the car comes to a stop without a problem, but it will be much more violent if the brakes suddenly brake.
In extreme cases, such as a collision with another vehicle or object, the force exerted on the object (car) will be greater and the impact will be much stronger and more dangerous. That is, the body will maintain the inertia of the movement it brought.
The same goes for the opposite. When the car comes to a complete stop and the driver accelerates sharply, our bodies tend to stay as they were (ie, at rest) and that’s why they tend to back off.
2- Car still moving
When trying to push a car, it is very difficult at first because, due to inertia, the car tends to remain stationary.
But, once activated, the effort that must be made is much less; since then, inertia keeps it moving.
3- The athlete who cannot stop
When an athlete tries to stop his career, it takes several meters to come to a complete stop, due to the inertia produced.
This is most clearly seen in track competitions such as 100 meters. Athletes continue to move far beyond the goal.
4- Futbol Theater … or not
In a football game, theatrical takedowns often occur between players of both teams. Often these falls can seem exaggerated when one of the athletes makes several turns on the grass after impact. The truth is that it is not always about histrionics, but about the Law of Inertia.
If a player comes running at high speed across the field and is rudely intercepted by someone on the opposing team, he is actually interrupting the rectilinear movement he was carrying, but his body tends to continue in the same direction and at that speed. That’s why the spectacular crash takes place.
5- The autonomous bicycle
Pedaling a bicycle allows it to continue advancing several meters without having to pedal, thanks to the inertia produced by the initial pedaling.
6- Up and down
Roller coasters can climb steep slopes thanks to the inertia produced by the previous steep descent, which allows them to accumulate potential energy to climb again.
7- Trick or science?
Many tricks that seem surprising are actually simple demonstrations of Newton’s first law.
This is the case, for example, of the waiter who can pull a tablecloth without falling objects on it.
This is due to the speed and force applied to the movement; objects that were at rest tend to stay that way.
8- Question of technique
A deck on a finger (or a cup) and, on the deck, a coin. Through a quick movement and force exerted on the deck, it will move, but the coin will remain immobile in the finger (or it will fall into the cup).
9 – Boiled egg vs raw egg
Another experiment to check the Law of Inertia can be done by taking a hard-boiled egg and rotating it on a flat surface and then manually stopping the movement.
The hard-boiled egg will stop immediately, but if we do exactly the same experiment as before with a raw egg, by trying to stop the egg’s rotational movement, we will see that it continues to rotate.
This is because the raw white and yolk are loose inside the egg and tend to keep moving once force is applied to stop it.
10- Tower of blocks
If a tower with several blocks is built and the lower block (the one that supports the weight of the others) is hit hard with a hammer, it will be possible to remove it without the rest falling, taking advantage of the inertia. Bodies that still tend to remain immobile.
The modern world could not be conceived as it is, were it not for the very important contributions of this Briton, considered by many to be one of the most important scientific geniuses of all times.
Perhaps without realizing it, many of the acts we perform in our daily lives constantly explain and confirm Newton’s theories.
In fact, many of the “tricks” that often surprise young and old at fairs or television programs are nothing more than a verification and a phenomenal explanation of the laws of dynamics, especially this first law of Newton or Law of Inertia
Having already understood that, if no other act acts on a body, it will remain stationary (at zero velocity) or will move indefinitely in a straight line with constant velocity, it is also necessary to explain that all movement is relative, as it depends on the subject who observes and describe this movement.
For example, the stewardess walking down the aisle of an airplane in flight, distributing coffee to passengers, walks slowly from the point of view of the passenger who is waiting in his seat for the coffee to arrive; but for someone who, from the ground, watches the plane fly by, if I could see the stewardess, I’d say it’s moving at high speed.
Thus, motion is relative and basically depends on the point or frame of reference used to describe it.
The inertial frame of reference is one used to observe bodies on which no force acts and therefore remain immobile and, if it moves, will continue to move at a constant speed.