Chapter 157: Perfect answer

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After that, it took Tang Zhifei a long time to calm down his emotions, wasting a small part of the lesson out of thin air before finally starting to speak Chinese.
As for the placement, although it is still a bit troublesome, it is also troublesome in June and July next year.
In front of us, there are imminent things.
That is Zhang Xiaoke's question.
"Three copies, one for each person, I will make the original version." Zhang Xiaoke put the question to Li Zheng and Jiang Qinghua, biting off the pen cap, full of momentum, quite a bit of Li Zheng's early style, "but want to taste a product, quiet There are many monsters in the quiet question."
"Right." Jiang Qinghua draws coldly. "Just for learning, not for reward. Let's go this way, right?"
Hearing this remark, Li Zheng felt for the first time that Jiang Qinghua was also a malleable talent.
After mixing for so long, it can be considered gradually, it's not bad.
Since it was a game, Li Zheng did not speed up cheating, but just looked down at the problem as usual.
Not to mention, although I have done a lot of chemistry problems recently.
But after looking at the physics question, it is still more intimate after all.
It's like a man who traversed the world and finally loved his hometown dish.
Li Zheng didn't think much anymore, and began to examine the subject--
[In August 2011, after the spacecraft "Chang'e 2" launched by our country completed the lunar exploration mission, it flew from the orbit around the moon to the Lagrange point on the extension line of the sun and the earth for the first time. 】
[At this point, "Chang'e 2" moves synchronously around the sun in a circular motion with the earth. 】
[It is known that the masses of the Sun and Earth are MS and ME, respectively, and the Sun-Earth distance is R. 】
[The distance x of the Lagrange 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 is.
It should be a physical problem.
But it's not that difficult.
It feels completely different from the first contact with competitive competition.
At that time, looking at those horrible compounds, it was totally confusing. They could only come by hard.
Because chemical competition involves a lot of chemistry knowledge at the undergraduate level, if you haven't learned chemical competition, it is a world of difference. You can't even read the questions.
However, Li Zheng can read and understand this question, and immediately has ideas, but he is not sure if he can solve it.
Lin Yuejing stole the study for so long, and everyone held back for another week without meeting.
Is it as simple as taking the physics question for greetings?
Can anyone who hasn't seen the physical competition at first glance try it?
Or am I too arrogant?
Maybe...difficult?
Li Zheng was not sure, so he had to do it first.
When examining this question, the only difficulty is probably "Lagrange point".
Li Zheng, steeped in sci-fi novels, is naturally familiar with this concept, but struggling with it only complicates this question.
In fact, to solve this problem, you don’t need to know what the "Lagrange point" is. You only need to pay attention to the key information given by the title-
1. This point is on the Sun-Earth extension line.
2. At this point, the spacecraft and the earth move synchronously around the sun in a circular motion.
Although these two points are textual descriptions, in the eyes of physics enthusiasts, they can be instantly transformed into geometric figures and mathematical expressions.
Since the spaceship is on the extension line of the sun and earth, it means that it is under the gravity of the earth and the sun, and the direction is the same. As long as the two gravitys 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, between the angular velocity of the circular motion, the radius, and the centripetal force, there is F=MRω^2
Next, you only need to list these equations and solve them simultaneously, junior high school mathematics.
In three or five minutes, the result of the first question came out.
The equation of the distance x of this point from the earth is-
MS/(R+X)^2+ME/X^2=MS(R+X)/R^3
This result is quite complicated, but the idea and calculation are really simple.
Look at the second question.
From this solution x≈_____.
Isn't this...the solution to the above equation...
Is this a math problem? ? ?
Looking at the equation above, it is clear that it is already too complicated, and it is impossible to solve it hardly with the mathematical knowledge we have now.
The reason is that (R+X)^2 on 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 a dazzling thing on the surface, it seems to have been shouting "If you don't look at me! Just look at me!"
That's the prompt in parentheses at the end.
(It is known that when λ<<1, (1+λ)^n≈1+nλ)
In addition to the final question, it is also x≈.
This is obvious.
You need to use this formula to simplify (R+X)^2.
After sorting out the ideas, first change (R+X)^2 to (1+λ)^n.
This becomes (1+X/R)^2R^2.
Then substitute the formula above...
Finally, the equation of the first question...
x≈{(ME/3MS)^1/3}R
Looking at this comfortable and beautiful answer, Li Zhengchang breathed a sigh of relief, and the whole person got up.
Cool.
It's cool to do physics questions.
Finally, there are half-mathematical questions.
happy!
Even though it has solved so many horrible chemistry questions, the coolness it brings is still not as good as this medium difficulty physics math question.
But, this difficulty...
Lin Yuejing, is it really the examiner?
If you want to stump Lao Tzu, at least some problems...
Is it possible that... she has other purposes?
Is there any goods hidden in this question?
Li Zheng could not help but look at the problem again
At Lagrange, the Chang'e 2 spacecraft circled synchronously.
These nouns, as well as the entire surrounding process, are already full of physical beauty.
Just like Lin Yuejing's composition called "Her Trip".
There is no formula in that composition.
Instead, it describes the entire physical process in a purely sensual and elegant way.
It seems……
X's solution is by no means the end.
The whole problem-solving process just now is to change these beautiful words into the formula above.
So now that the results are out, you might as well translate the digital results back into the perceptual text.
From this perspective, the final question is no longer x≈what.
It is Chang'e II, how far must it fly to dance with the eternal sun of the earth.
Li Zheng's eyes shrank.
The heart thumped.
NO.
No.
No..
This is not a physics question.
It is a metaphorical suggestion.
My Li Zheng belongs to the earth, equal to the earth.
Your Lin Yujing is a woman, equal to Chang'e.
The sun is the eternal center, the original heart and faith, which is equal to physics.
Convert it.
You Lin Yuejing, want to be with my Li Zheng and enter the arms of physics.
How far will it go?
Thinking of this, Li Zheng looked upset.
what!
I understand.
Wonderful!
It is Lin Yujing who knew you would not have such a simple question.
You are implying that you want to join me in this physics college, right?
If I read your hint, fill in that answer, right?
Interesting, such a question is interesting.
Without thinking, Li Zheng pinched his fingers.
This puts an equal sign on the solution of X and fills in the real answer--
【564】
564 days before the college entrance examination!