Learning Demon Cultivation System

But it still didn't hide the faint unwillingness.

The whole class was silent.

No one applauded, and no one echoed.

Only a touch of sadness.

This is probably the sorrow of ordinary class teachers.

He has worked so hard to train the best student, but he has to watch him go to the key class.

The more attentively you cultivate, the more gratifying the result will be, and the more you will lose.

Given the atmosphere is so pathetic.

Li Zheng raised his hand proactively.

"You are the only one not allowed to speak." Tang Zhifei immediately raised his arms and turned his face away, "I know what you are going to say, 'make our class a key class', 'just let the whole class enter the key class', right? It’s unrealistic, you have to talk about it yourself after class.”

"No." Li Zheng said, "For me, it doesn't matter who teaches which class. If I tell Principal Liu not to transfer classes, he probably won't have any opinion. So, Mr. Tang, don't be so sad, I will The ones left..."

Immediately, there was an uproar.

"Woooooo!!"

"what!"

"Brother Li is so loyal!"

"Hmm!" Lin Yujing got up in a start from sleeping on her stomach.

Looking at Li Zheng.

There are only two big characters in my eyes——

EQ!

She immediately raised her hand and said, "I like Teacher Tang, and I won't leave either."

This time, the coaxing was even louder.

You make it clear.

Do you just like Teacher Tang?

Zhang Xiaoke also raised his hand: "If they don't leave, I won't leave either."

Jiang Qinghua had no choice but to raise his hand and said, "I am willing to be Teacher Tang's monitor forever."

The usually shy Liu Yuexuan also nodded excitedly: "Me too, I want to be Teacher Tang's class representative."

Tang Zhifei covered his face in fright, turned his back, shook his hands vigorously and said, "No, no, no, absolutely no! This is not your own business. Parents should be anxious if you do this, and the school should also be anxious. The top students don't go to key classes. , Isn’t this a blatant provocation? In the end, I will still let me do the work, so don’t hurt me!”

Li Zheng immediately nodded and said, "Don't panic, I'll talk to the school."

"Shut up!" Tang Zhifei turned his back and wiped his eyes and said, "If you talk again, I will go out and stand for punishment!"

Chapter 158 The Perfect Answer

After that, it took Tang Zhifei a long time to calm down. He wasted half of the class out of thin air before finally starting to speak Chinese.

As for the division of classes, although there are still some troubles, it will be troubles in June and July next year.

In front of you, there are things that are imminent.

That is the question that Zhang Xiaoke copied.

"Three, one for each person, I'll make the original." After Zhang Xiaoke stuffed the question to Li Zheng and Jiang Qinghua, he bit off the cap of the pen, full of momentum, quite a bit of Li Zheng's early demeanor, "I'd like to taste one product, quietly. How enchanting are the quiet questions."

"That's right." Jiang Qinghua drew his pen sternly, "It's just for learning, not for rewards. That's the way we're going, right?"

Hearing this, Li Zheng felt for the first time that Jiang Qinghua was also a malleable talent.

After mixing for so long, it can be regarded as gradually getting on the road, which is not bad.

Since it was a competition, Li Zheng didn't speed up and cheat, but just lowered his head and aimed at the question as before.

Not to mention, although I have done a lot of chemistry problems recently.

But after looking at the physics questions, it is still more intimate after all.

It's like a man who has traveled through the world, and finally fell in love with that mouthful of hometown food.

Li Zheng stopped thinking about it and began to examine the questions——

[In August 2011, after completing the lunar exploration mission, the spacecraft "Chang'e-8" launched by our country flew for the first time from the orbit around the moon to the Lagrangian point on the extension line of the sun and the earth. 】

[At this point, "Chang'e-[-]" and the earth move synchronously around the sun in a circular motion. 】

[It is known that the masses of the sun and the earth are MS and ME respectively, and the distance between the sun and the earth is R. 】

[The distance x of the Lagrangian point from the earth satisfies the equation _______. 】

【The solution is x≈________. (It is known that when λ<<1, (1+λ)^n≈1+nλ)

Li Zheng's first reaction after reading the question was.

It should be a matter of contention.

But it's not that hard.

It is completely different from the feeling of contacting the competition for the first time.

At that time, looking at those terrifying compounds, I was completely at a loss.

Because chemistry competition involves a lot of chemistry knowledge at the undergraduate level, it is a world of difference if you have never studied chemistry, and you often can't even understand the questions.

But Li Zheng could understand this matter competition problem, and immediately had an idea, but he was not sure he could solve it.

Lin Yujing had been studying secretly for so long, and everyone held back for another week without seeing each other.

Is it that simple to take out the physics question for greetings?

I, a person who has never seen Wujing at a glance, can give it a try?

Or am I being too arrogant?

Maybe... Difficult?

Li Zheng wasn't sure, so he had to do it first.

When reviewing this question, the only little difficulty is probably the "Lagrangian point".

Li Zheng, who is steeped in science fiction, is naturally familiar with this concept, but being entangled in it will only complicate the question.

In fact, to solve this question, you don't need to know what a "Lagrangian point" is, you just need to pay attention to the key information given on the question face——

1. This point is on the sun-earth extension line.

2. At this point, the spaceship and the earth make a circular motion around the sun synchronously.

Although these two points are described in words, in the eyes of physics lovers, they can be transformed into geometric diagrams and mathematical formulas in an instant.

Since the spacecraft is on the extension line of the sun and the earth, it means that it is subjected to the gravitational force of the earth and the sun in the same direction. As long as the two gravitational forces are added together, it is the centripetal force of the circular motion of the spacecraft.

Since it orbits the sun synchronously with the earth, it means that the angular velocity ω is the same.

At the same time, there is F=MRω^2 between the circular motion angular velocity, radius, and centripetal force

Next, you only need to list these equations and solve them simultaneously. Junior high school mathematics.

In three to five minutes, the result of the first question came out.

The distance x of the point from the earth satisfies the equation——

MS/(R+X)^2+ME/X^2=MS(R+X)/R^3

This result is quite complicated, but the ideas and calculations are really simple.

Look at the second question.

From this solution x≈_____.

This...isn't it just solving the above equation...

This is a math problem, right? ? ?

Looking at the above equation again, it is obvious that it is already too complicated, and it is impossible to solve it by force with the current mathematical knowledge.

The reason is the (R+X)^2 on the denominator of the first column of the equation, which directly pulls the equation into the abyss.

But Li Zheng didn't panic.

Just because there is something dazzling on the title, as if it keeps shouting "If you don't, just look at me! If you don't, just look at me!"

That's the hint in parentheses at the end.

(It is known that when λ<<1, (1+λ)^n≈1+nλ)

Plus the last question, also x≈.

That's pretty obvious.

You need to use this formula to simplify (R+X)^2.

After clarifying the idea, first change the form of (R+X)^2 to (1+λ)^n.

This becomes (1+X/R)^2R^2.

Then substitute into the above formula...

Finally, combine the equation of the first question...

x≈{(ME/3MS)^1/3}R

Seeing this comfortable and beautiful answer, Li Zheng breathed a sigh of relief, and his whole body became refreshed.

cool.

It's still cool to do physics problems.

Finally, there is half a math problem to refresh the taste.

happy!

Even after solving so many scary chemistry problems, the refreshing feeling it brings is still not as good as this medium-difficulty physics and mathematics problem.

It's just that this difficulty...

Lin Yujing, are you really testing people?

If you want to stump me, at least come up with some difficult problems...

Could it be... She has other purposes?

Is there something hidden in this question?

Li Zheng couldn't help looking at the title again.

At the Lagrangian point, the Chang'e-[-] spacecraft orbits synchronously.

These nouns, as well as the entire surrounding process, are full of physical beauty.

Just like Lin Yujing's essay titled "Her Travel".

In that composition, there is no half formula.

Instead, it describes the entire physical process in a purely sensual and elegant way.

It seems……

The solution of X is by no means the end.

The entire problem-solving process just now is to transform these beautiful words into the formula above.

So now that the result is out, you might as well translate the numerical result back into perceptual text.

Viewed from this perspective, the ultimate question is no longer what x ≈ what.

It's about how far Chang'e-[-] has to fly before it can dance with the earth's eternal circumnavigation of the sun.

Li Zheng narrowed his eyes.

The heart was beating loudly.