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

As for the division of classes, although there are still some problems, that will be a problem in June and July next year.

There are still pressing matters before us.

That was the question Zhang Xiaoke copied.

"Three pictures, one for each person. I will make the original version." After Zhang Xiaoke handed the questions to Li Zheng and Jiang Qinghua, he bit open the pen cap and said with full momentum, quite a bit like Li Zheng's early style, "I want to taste it, Jing Jing

What a ridiculous question Jing asked."

"That's right." Jiang Qinghua drew the pen sternly, "It's just for learning, not for rewards. This is the path we are taking, right?"

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

After being around for so long, I’m gradually getting on the right track, which is pretty good.

Since it was a competition, Li Zheng did not speed up and cheat, but just lowered his head and looked at the question as before.

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

But when I look at the physics questions, they are more approachable after all.

It's like a man who has gone through all the troubles in the world, but what he loves in the end is the local food.

Li Zheng stopped thinking about it and started reviewing the questions.

[In August 2011, the spacecraft "Chang'e 2" launched by our country completed its lunar exploration mission and flew from the lunar orbit to the Lagrange point on the Sun-Earth extension line for the first time. 】

[At this point, "Chang'e-2" and the Earth are synchronously moving in a circular motion around the sun. ]

[It is known that the masses of the sun and the earth are respectively, and the distance between the sun and the earth is r.]

[The equation satisfied by the distance x of the Lagrangian point from the earth is _______.]

[This solution yields x≈________. (It is known that when λlt;lt;1, (1+λ)^n≈1+nλ)

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

It should be a matter of competition.

But it's not that difficult.

It feels completely different from the first time I came into contact with a competitive competition.

At that time, when I looked at those terrifying compounds, I was completely confused, so I had to try hard and try to mix them up.

Because Chemistry Competition involves a lot of undergraduate-level chemistry knowledge, there is a huge difference between those who have studied Chemistry Competition and those who have not, and often cannot even understand the questions.

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

Lin Yujing had been secretly studying for so long, and everyone didn't see each other for another week.

Is it that simple to come up with a physics question for greetings?

Can a person like me, who has never seen Wu Jing, give it a try?

Or am I too arrogant?

Maybe... it's difficult?

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

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

Li Zheng, who is immersed in science fiction novels, is naturally familiar with this concept, but getting entangled in it will only make this question more complicated.

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 in the question.

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

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

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

Since the spacecraft is on the sun-Earth extension line, it means that it is subject to the gravitational pull of the earth and the sun in the same direction. As long as the two gravitational forces are added, 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 speed is the same.

At the same time, between the angular velocity of circular motion, radius, and centripetal force, r^2

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 between the point and the earth satisfies the equation:

ms/(r+x)^2+me/x^s(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 we get x≈_____.

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

Is this a math problem???

Looking at the above equation again, it is obvious that it is too complicated. It is impossible to solve it hard with the mathematical knowledge we have now.

The reason lies in (r+x)^2 in the denominator of the first column of the equation. This thing directly pulls the equation into the abyss.

But Li Zheng did not panic.

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

That's the tip in parentheses at the end.

(It is known that when λlt;lt;1, (1+λ)^n≈1+nλ)

In addition, the last question is also x≈.

This is 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 the above formula...

Finally, combine the equations of the first question...)^1/3}

Seeing this comfortable and beautiful answer, Li Zheng breathed a long sigh of relief and became energetic.

So cool.

It’s still fun to do physics questions.

Finally, there is half a math question to add to the flavor.

happy!

Even though I have solved so many scary chemistry questions, the feeling of satisfaction is still not as good as this moderately difficult physics and mathematics question.

It's just that this difficulty...

Lin Yujing, is she really taking a test?

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

Could it be that...she has other purposes?

Is there something hidden in this question?

Li Zheng couldn't help but look at the topic again.

Lagrange point, Chang'e-2 spacecraft, synchronously orbiting.

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

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

There is no formula in that essay.

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

It seems……

The solution to x is by no means the end point.

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

So now that the results are out, you might as well translate the numerical results back into perceptual words.

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

It’s about how far Chang’e 2 must fly before it can dance with the Earth forever around the sun.

Li Zheng's eyes narrowed.

My heart skipped a beat.
To be continued...