This article was originally written yesterday, but yesterday I watched the Wandering Earth 2, and the 3 -hour movie can only be left today.

Of course, today’s theme is not to be funny.

When we first heard “what is exercise”, the first reaction was: this is really simple.

Apple landing is sports;

From behind, I had a classmate, and he would definitely exercise;

Seeing a beautiful flower, it was the result of the movement (the photon ran into the eyes);

The whispering sound that I heard is also a kind of movement (the sound waves are passed into the ears through the air) …

Exercise is everywhere, the essence of time is the movement of material.

But it is such a seemingly bland thing, but it is full of physics. Physics studies their movement laws, studying why they exercise, and how to exercise.

If there is no exercise, the world will be a dead silence. Can you imagine a world without sports?

In essence, exercise is simple, that is, the material moves from point A to point B, or point C to point D. The operation of the entire universe is built on such a simple movement.

But why the exercise in physics is so complicated? Many laws such as Newton’s three laws, the laws of gravity, and the laws of Kulun are used to describe the movement.

In fact, the essence of the universe is not complicated, but it is complicated to turn them into things that are beneficial to humans and what people understand, just like the essence of the computer is 0 and 1.It will also be converted to 0 and 1, but we cannot directly enter 0 and 1 to operate.

Since the exercise is so obvious and nowhere, why does the object exercise?

When you think about it carefully, you will find that it is not as simple and taken for granted.

A iron ball falls faster than a feathers because of the heavier iron ball?

The balloon flies up, and Apple falls because Apple is heavier?

If you push the desk, go forward, and the desk is stopped. Do you have to have external forces to move the object?

These common phenomena, when we are ready to answer carefully, we find that it is not as simple as imagined.

Thinking is not the patent of modern people. In ancient Greece, many natural philosophers thought about these issues, but the answers were not very satisfactory.

Back to the above examples, when you push the desk, the desk is moved. This is better to understand, and it is easy to accept through contact.

But when Apple falls, there is nothing to contact with it. Why is it still exercising?

When the hot air balloon rises, there is nothing to contact with it. Why does it exercise up?

Moreover, why do Apple move down, but the balloon moves up?Could it be that heavy things have fallen, and all the light things fly up?

Of course, friends who grew up under physics know that Apple’s whereabouts are due to the downward gravity, and the balloon rising is because of the upward buoyancy.

But today’s article is not about gravity and buoyancy, but to talk about the knowledge system behind “exercise”, and how this scientific system is formed.

There was no science in the ancient Greek period. At that time, the scientific work was all philosophy.

The reason was that at that time, there was very little understanding of nature, and one person could do it.

When the ancient Greeks carried out a detailed analysis and in -depth philosophical thinking on nature, they finally formed a self -consistent natural philosophical system.

The development of physics to this day is also a generation on the shoulders of a generation, and the results obtained by constantly exploring and accumulating. Einstein was born in ancient Greece.

In the process of accumulation, there is a core figure we can’t get around, that is, the famous Aristotle.

Don’t underestimate the world view of Aristotle, it has ruled Europe for nearly 2000 years until the emergence of Galileo.

This set of views believes that the earth is the center of the universe, and the sun, moon and stars are around the earth.

This is a mistake that modern elementary school students can point out, but at the time it was very amazing. When Aristotle looked up at the starry sky, he had begun to find the truth of the universe through the obstacles of God and opened the natural philosophy exploration of natural philosophy.The door.

He attributed the movement of the world to four basic elements: qi, soil, water, and fire.

For example, the element of fire has a trend that is naturally far from the center of the universe, so the fire burns upward in the air.

Aristotle believes that a static object will always remain still. Unless it has other sources of movement, it is either moved to the natural position of the universe or the outside world, such as pushing a table.

His system is huge. This is just a point of view from his theory. It is convenient for everyone to understand. It is a self -consistent system.

His worldview can also explain why the object is exercising, and can make the ancients understand the various phenomena they see.

Although this explanation is “naive” in our opinion, because it is easy to be understood and accepted, it was treated as truth at the time.

It was not until the appearance of Galileo in the 17th century that Aristotle had ruled the world view of nearly two thousand years in Europe.

Natural philosophy began to go to science.

Galileo believes that everyone should not engage in idealism. It is necessary to use data to seek truth from facts. Seeing can be true, but not true, only the test of mathematics can be true.

He opened the metaphysical, and unable to quantify from the purpose and nature of discussing objects and nature.

Simply put, the focus is on the quantitative calculation from qualitative analysis.

For example, now you see the balloon rising, noBe able toAs before, it was simply summarized as the buoyancy of air upward, and the buoyancy of the water was also used from time to time.

Now you have to know what the air buoyancy is and the weight of the balloon. In this weight, how high the balloon rises in the first second, how high it rises in the second second.

Then summarize their laws, and then frame the laws with formulas and theorems. In different spaces and different times, the same test is performed to verify whether the law is conservative. Only the laws of conservation can become scientific truth.

Of course, Galileo is a practitioner of Zhiyi, and he immediately conducts quantitative calculations for the qualitative analysis of Aristotle.

Since Aristotle said that all objects reach its natural position, it will be static, then Galileo has verified whether it is because of experiments.

Galileo first started with exercise.

He designed a U -shaped prop. In a smooth slope, no matter how tall the ball is from the left, the small ball can basically return to the same height on the right.

Progressive layer: When the slope on the right is constantly reduced, so that the right side is more and more usual. To return to the same height, the small ball has to exercise a farther distance.

Finally, the right slope was completely flattened, and the right side became a plane, and the height never changed.In this way, no matter how long the ball is, how far exercise, it is impossible to return to the height on the left.

It means that the height of the left will always be: the small ball will continue to move in line at a uniform speed (assuming that the ground is absolutely smooth, the friction is 0), until it encounters other obstacles.

Galileo found out from a series of slope experiments: Whether an object is moving, it is not directly related to whether it is in force, and the exercise does not require external forces to maintain it.

Let’s talk about it twice:

1. Exercise does not require external forces to maintain;

Second, exercise does not require external forces to maintain.

In other words, the exercise itself does not need to be maintained, and the object can also maintain the state of a uniform straight movement when the object is not affected by any external force.

Is it a bit embarrassing? Back to the above mentioned: When we push the table hard, the status of the desk has indeed changed, and it seems that the greater the strength we use, the greater the chair speed, but the exercise but exercise but the exercise but exerciseThere is no need to maintain external forces. So, what is the role of power?

Galileo did further research on these issues, and finally found that force is not the reason for maintaining object movements, but the reason for changing the state of object movement.

In other words, maintaining the movement of objects does not require force, but changing the movement of objects requires force, and the role of force cannot be ignored.

Not only cannot be ignored, but also a lot of flower work later, such as: What is the relationship between the size of the force and the speed of speed?The greater the strength, the greater the speed changes?

For another example: We know that power can change the state of movement of the object, so how much force should we change to change the movement direction and speed of a certain weight?

Did these problems make you think of a very familiar person?have toLet us say his name loudly: Newton!

However, Niu Ye justAbsenceThe chapter has begun, and the next chapter will focus on Newtonian mechanics.