Chapter 158

After that, Tang Zhifei took a long time to calm down his mood and wasted half of his class. Finally, he began to speak Chinese.

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

Now, there is something urgent.

That's the question that Zhang Xiao can copy.

"Three, one for each, I'll make the original." After Zhang Xiaoke put the title to Li Zheng and Jiang Qinghua, he bit off the pen cap, which was full of momentum. He had some of Li Zheng's early demeanor. "I want to have a product, but I have to write a question quietly."

"Yes." Jiang Qinghua drew his pen coldly. "It's just for study, not for reward. This is the way we're going, right?"

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

After mixing for so long, it can be regarded as gradually getting on the road. It's good.

Since it was a competition, Li Zheng did not speed up cheating, just looked down at the problem as before.

Don't say, although I have done a lot of chemistry problems recently.

But a look at the physics problem, after all, or more intimate.

It's like a man, traversing the world's dust, and finally falling in love with that home dish.

Li Zheng stopped thinking and began to examine the topic -

[in August 2011, after the completion of the lunar exploration mission by China's spacecraft Chang'e-2, it was the first time for China to fly from orbit around the moon to the Lagrange point on the sun earth extension line. 】

[at this point, Chang'e-2 and the earth move in circles around the sun synchronously. 】The mass of the sun and the earth are known to be MS and me, respectively, and the sun earth distance is r. 】

[the distance X of the Lagrange point from the earth satisfies the equation ﹥ uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu. 】

[from this solution, X ≈ uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu. (it is known that when λ 1, (1 + λ) ^ n ≈ 1 + n λ)

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

It should be a matter of competition.

But it's not that hard.

It is totally different from the feeling of first contact with competitive questions.

At that time, when we looked at those horrible compounds, we were at a loss. We could only make them hard and mix them up.

Because chemical competition involves a lot of undergraduate level chemical knowledge, and if you have not studied chemical competition, it is a big difference. You often can't read the questions.

However, Li Zheng could understand this question and immediately had a train of thought, but he was not sure that he could solve it.

Lin qiojing has been learning for so long that we haven't seen each other for another week.

Take out the physics question of greeting, is it so simple?

Can anyone who hasn't seen the competition have a try?

Or am I too arrogant?

Maybe Hard?

Li Zheng was not sure, so he had to do it first.

When examining this problem, the only difficulty is probably "Lagrange point".

Li Zheng, who is steeped in science fiction, is naturally familiar with this concept, but entangled in it will only make the problem more complicated.

In fact, to solve this problem, we don't need to know what the "Lagrange point" is at all. We only need to pay attention to the key information given on the problem surface -

1, which is on the sun earth extension line.

2. At this point, the spacecraft and the earth move in circles around the sun synchronously.

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

Since the spacecraft is on the solar terrestrial extension line, it means that it is subject to the gravity of the earth and the sun, with the same direction. As long as the two gravities are added together, it is the centripetal force of the spacecraft's circular motion.

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 = Mr ω ^ 2

between the angular velocity of circular motion, radius, and centripetal force. Next, we only need to list these equations and solve them simultaneously. Junior high school mathematics.

After three or five minutes, the result of the first question came out.

The equation of the distance X between the point and the earth is -

MS (R + x) ^ 2 + mex ^ 2 = MS (R + x) R ^ 3

this result is quite complicated, but the idea and calculation are really simple.

Let's look at the second question.

From this solution, X ≈ uuuuuuuuuuuu is obtained.

This Is not to solve the above equation

Is this a math problem???

If you look at the above equation, it is obvious that it is too complicated. It is impossible to solve it with the knowledge of mathematics.

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

But Li Zheng did not panic.

Just because there is a glaring thing on the surface of the title, it seems to have been shouting, "it won't just look at me! Not just me

That's the last hint in brackets.

(when λ 1 is known, (1 + λ) ^ n ≈ 1 + n λ)In addition, the last problem is x ≈.

This is obvious.

We 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.

So it becomes (1 + XR) ^ 2R ^ 2.

And then put in the formula above

Finally, we combine the equations of the first question

X ≈ {(me3ms) ^ 13} r

looking at the comfortable and beautiful answer, Li Zhengchang breathed a sigh of relief, and the whole person was in spirits.

Cool.

It's cool to do physics.

Finally, there are half of the math problems.

Happy!

Even if we have solved so many terrible chemistry problems, the feeling of pleasure is still not as good as this middle difficulty physics and mathematics problem.

It's just, this difficulty

Lin qiojing, is he really testing people?

If you want to defeat Laozi, at least come to some problems

Is it difficult to Other purposes?

Is there any goods hidden in this question?

Li Zheng couldn't help looking at the Lagrange point of the topic again, and the Chang'e-2 spacecraft circled synchronously.

These nouns, and the whole process of encirclement, are full of physical beauty.

Just like Lin qiojing's composition entitled "her journey".

There is no half formula in that composition.

It describes the whole physical process in a purely emotional and elegant way.

So

The solution of X is by no means the end point.

Just the whole problem-solving process, is to change these beautiful words into the formula above.

Now that the results are out, we might as well translate the numerical results back into perceptual words.

From this point of view, the final question is no longer what x ≈ is.

It's Chang'e-2. How far does it have to fly to dance with the earth's eternal circle of the sun.

Li Zheng's eyes shrunk.

The heart thumped up.

< br.

It's a metaphor.

Li Zheng belongs to earth, equal to the earth.

You Lin Yue Jing is a woman, equal to Chang'e.

The sun is the eternal center, the original heart and belief, equal to physics.

It's converted.

You, Lin Yujing, want to be with me, Li Zheng, and enter the arms of physics.

How far is it going?

Thinking of this, Li Zheng's face showed joy.

Ha!

I understand.

Wonderful!

Lin Yue Jing deserves to know that you will not be so simple questions.

You're implying that you're going to join me at Ji University, aren't you?

If I read your hint, I'll fill in the answer, right?

Interesting, such a question is interesting.

Without thinking, Li Zheng calculated.

An equal sign is added to the solution of X and the real answer is filled in -

< 564]

there are 564 days to go before the college entrance examination!

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