Among them, he talked about several aspects. I'll just say a few things that interest me most.
The first aspect is the sum of pi.
It says that if you divide the circumference of a circle by the diameter of the circle, you can calculate a number starting with 3. 14, right? Is this really the case?
In our math group, I talk about pi with teacher Song Song. Teacher Song Song said, if we divide the circumference of a circle by the diameter of the circle according to the method in the documentary, will the calculated quotients be around 3. 14 or 3. 14?
I tried to find some to sit down, and I found this. But I actually made five * * *, but only three were presented, because I didn't understand two of them when I calculated. I told Song Song that maybe it was because there was an error in the middle, maybe it was not a circle, or maybe I didn't measure it well. Because there is no soft ruler at home, you can only wrap it up with a headphone cord first, and then measure it with a ruler, which is a bit wrong. ) and the calculated decimal starting with 1. 14 is called π.
Among them, π is everywhere in our life. For example, at the corner of the coastline of the river bend, the changing ripples on the sand dunes all contain π. Including when the air conditioning blades swing up and down, does π exist in every corner of the road? !
There is a man named Sam who has been fishing for 40 years and can catch an average of 200 fish every day. So, how many fish can he catch a year? How many times has he succeeded in his life? On average, it can reach 200x365 articles per year, or 73,000 articles. Then he said that he had been fishing for 40 years, and then multiplied by 40, 73,000 fish were the fish he had caught in his life, about 2.92 million. (Because he said it can reach about 200 a day. )
Small theater:
So how do you find the circumference of a circle? In fact, it is the same as multiplication and division, that is, the circumference of a circle divided by its diameter is 3. 14, so conversely, 3. 14 multiplied by the diameter of that circle is the circumference of that circle.
The second interesting thing is negative numbers.
Plural numbers are really mysterious. For example, 1 fish plus-1 fish equals 0 fish. This may be difficult to understand, but this example is not difficult to understand.
You dig a hole, the hole is negative one, and then you dig the soil out of the hole, and the soil is one. Bury in this negative pit again, and you won't pit. And whether it is the multiplication of complex numbers or the multiplication of integers, its product is an integer.
Example:
1× 1= 1? - 1×- 1= 1
It may be hard to believe, but it's true. But generally speaking, there is a special case.
? ×? =- 1 Many people may ask why. Don't ask me, I don't know. This problem has not been fully studied in the field of mathematics. But you can think about why.
The third is the growth rate of nautilus shells.
After measurement, we found a secret. Nautilus shell can not only create such a perfect rotation, but also each chamber is 1.08 times the previous one, which proves that Nautilus grows at a constant speed. I was really surprised to learn about it. There are still people in the world who can create the life of a mathematics practitioner, and create it so beautifully.
The fourth thing I am interested in is gravity.
After throwing a stone with a catapult, he will accelerate to the ground at a speed of 9.8 meters per square second, but in fact he is slowly slowing down. In fact, it seems that he obviously accelerated when he fell, but why did he say that he has been slowing down? I'm not sure about that either.
This is my opinion on this documentary.