Chapter 242: Xuepi

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In a small classroom, he closed the door like a stream of clouds, opened the window, sat on the podium, and smoked.
This series of actions is done in one go, and there is no sense of culture.
This is probably the legendary scholarship.
Li Zheng's behavior is completely opposite to him. He put his schoolbag, his stationery, his notebook in order and sat upright.
Xie Qi looked at this series of movements and couldn't help but sigh: "Just give him a national grade three good students."
"Ah? Sanhaosheng still has a national level?" Li Zheng inevitably eager to try.
Xie Qi laughed and said: "Yes, all, and world-class, go to Moscow to review, Lenin awards."
"Boring." Li Zheng thought about it for a moment, and soon discovered the inadequacies. "No, are you saying that this is an excellent member?"
"...You are really... quite serious." Xie Qi asked a little, and said, "Which part of physics do you want to listen to? Anything except quantum mechanics."
"Ah? I just want to hear Quantum." Li Zheng said, holding the stationery and sitting in the last row of the classroom, it tasted less.
"Quantum mechanics is an MLM organization, and the people themselves don't know what to do." Xie Qi resolutely waved his hand. "Hurry, change one."
"Then listen to your more specialized field." Li Zheng replied.
Xie Qifan waved his hand more firmly: "No, you can't understand what I'm doing, and I'm too lazy to talk about what you understand, even if you understand it, it's not good for your future."
Li Zheng complained: "What are you doing in a lecture?"
"I'll talk to you about perpetual motion again."
"Don't don't..." Li Zheng scratched his head and said, "Then let's talk about fluid mechanics. I haven't learned this part well."
"Normal." Xie Qi said with a mouthful of smoke, "Lagrangian description, Euler description, Bernoulli equation all know?"
"Yes, but not deep."
"Then I ask you, what does this brother have in common?"
"Um..." Li Zheng answered almost without thinking, "All are mathematicians."
"Oh, yes!" Xie Qi was happy, jumped off the desk with a cigarette, and walked to the blackboard, "turn the laws of physics into mathematical equations, then cut the fluid into small pieces, and use the calculus idea to solve, This is fluid mechanics. Of course, this is just Lagrange’s way. Euler’s method is more wild. Say one more thing. All physical problems can be solved with this routine if you want to.

"Ah." Li Zheng glared, "Isn't that...come to the wind?"
"Yes, I heard about him from the number school." Xie Qi nodded. "His understanding of physics concepts is basically limited to high school textbooks. It has always been converted into mathematical ideas to solve problems. The number school has invited him to go long ago. He listened, but he didn't go much."
"Ah... don't mention him." Li Zheng urged, "You continue to talk."
"Well, let me tell you about Lagrange's description first." Xie Qifan drew a picture on the blackboard, which is probably a pool of water, cut it in different ways, and then drawn a series of schematic diagrams of the force.
"This is the most basic physical image of fluid analysis."
"We need to use physical images as a hub to connect the mathematical world."
"Of course top geniuses don't need this stuff, they have a translation system in their brain circuits."
"For example, von Neumann, he also did this, but it was done when Fermi and Feynman made the atomic bomb together. When he got together, Fermi was old and used a slide rule, Feynman. Young, using a computer, Von Neumann doesn’t need anything, even mentally, the result is always faster than the two brothers."
"Then the atomic bomb experiment was successful, and the brothers went home after work. As a result, von Neumann's mental calculation came up with a'Neumann stability analysis', which directly blossomed in mathematical physics, but unfortunately it was an atomic bomb. When I came up with it, it was directly kept secret by the magnesium military for ten years."
"Unfortunately, old Feng left in his 50s..."
Upon hearing this, Li Zheng couldn't help but raise his hand: "Teacher Xie, although I rarely listen to crosstalk, why does it feel like I've reached Deyun Society?"
"Eh? You also listen to Teacher Guo and Teacher Yu? I listen to Chengsu, do you have the energy to speak?"
"This...I don't reject this kind of energy, but you only talk about 15 minutes."
"Fuck, this time doesn't count... you see this Tuo fluid, three-dimensional, we are now slightly in the x direction..."
"Then the y direction, the z direction..."
"The three directions are all together, this is the big equation, this is the continuous equation description."
"With this, some laws of physics can be applied randomly, and others can be introduced."
"For example, the speed at a certain moment, you can use the momentum theorem."
"For the first time, I'll take you one set first. In fact, these two formulas...the whole one will be slightly more..."
"...The equation is finally derived, is it good-looking?"
"Oh, by the way, this is the Navistokes equation. You can use it directly if you can back it down. It doesn't matter if you can't back it down. Just like I pushed it so hard."
"Sometimes I'm not wrong, too many equations, it's not as comfortable as pushing it out."
"In addition, momentum theorem is not necessarily used here. Another set of physics laws that can construct the relationship between time and velocity can also be derived from this equation. You can try it yourself if you have nothing to do. I will not talk about it."
"Okay." Xie Qi threw chalk and clapped his hands. "That's all. Now you should be able to deduce all the equations of fluid mechanics. Some places use linear algebra, so you won't learn it yourself."
Li Zheng: "???
"Huh? Is there anything else I don't understand?"
"Ah..." Li Zheng shook his head.
It's not a problem that I don't understand.
I don't even know what I should understand!
Li Zheng asked daringly: "For example... the flow of viscous fluid in the tube."
"Isn't it just a matter of putting a few tubes and adding a few forces together to get rid of it?"
"Really... Then I look at it..." Li Zheng shivered and picked up the pen.
"Well, stay tuned, don’t ask if you don’t understand, just flip the book back equation. I’ve taught everything here. I can derive the whole set of pictures by the simplest theory. This is the basis of physics. Quality."
"Really...the foundation..." Li Zheng has begun to sweat.
After that, Xie Qifan left the small classroom and went to the laboratory.
In desperation, Li Zheng had to use his thinking to accelerate.
Although it is very nonsense, but solving their differences does indeed provide a set of learning methods-
Derived by yourself.
Of course, at least a full grasp of advanced mathematics and linear algebra is required to qualify.
Presumably, Gui Jianfeng must have mastered it already.
And every time the physical examination is pushed so hard.
No, it should have started a long time ago.
Maybe he pushed it all over the whole middle school.
Or earlier, elementary school.
This has even been the case since the numbers were touched.
Presumably, whether it is to see the wind or to resolve its disputes, from the beginning, instinctively chose this set of ideas. In the derivation of tens of millions of times, it strengthened his brain again and again, and finally became stronger than nothing. .
Of course, perhaps the congenital reason is the dominant one, but this does not prevent the acquired training from functioning.
Give it a try.
Follow the path of these perverted geniuses.
Li Zheng started with all his strength and embarked on a learning path that had never been taken before.
...
Half an hour later, when Xie Qi returned to the classroom, he saw scratch papers all over the place.
"Relief, are you really pushing?" Xie Qi walked close to Li Zheng in surprise, and picked up a piece of draft paper to look up. "Well... that's the case..."
Li Zheng himself has also escaped from the acceleration of thinking, and his eyes are empty, breathing heavily.
He used this learning method to live so much. In the first few hours, he was struggling. More often, he could only use the brute force method to apply various physical formulas in order to calculate the required equations.
It's like throwing a pile of screws and nuts of different shapes to a blind man. Let him screw together. The blind man can only touch the outline to try one by one.
But after the 8th hour, Li Zheng gradually had vision, or, his sense of touch became more acute.
He can only see the shape of the nut and know what kind of screw he needs.
After 30 hours, he can clearly see most of the details of the nut and completely determine what size screw he needs.
After 45 hours, he knew exactly where each screw was.
After 55 hours, he closed his eyes again and returned to the original state. He only needed a light touch on the nut to twist the required screw.
At this moment, Li Zheng stared forward.
He did not feel that he had learned anything.
But confidently understand everything.
No matter what problems are thrown, he has a solution.
Feeling mysterious self-confidence.
Li Zheng's entire scalp numb.
Is a new realm!
No tricks, no tricks!
At this moment, Xuzhu is not alone.
Feng Qingyang, Zhang Sanfeng, Du Gu seeking defeat, at this moment the soul unites!
"I... I get it..." Li Zheng looked at Jie Qi and grateful, "Thank you Teacher Xie, thank you!!!"
"..." Xie Qi held the scratch paper and took a step back. "I... I didn't do anything. Just call me Old Solution. Crab is my nickname, only my mother can call it."
"thanks, thanks!"
"..." Xie Qi looked at Li Zheng with anxiety, and picked up two draft papers for a moment, and couldn't help sighing, "It's not easy to get so much... but you can see that you are average mathematics, method It’s stupid. To be honest, we still can’t match...I’m not sure I can continue to teach you.

"It doesn't matter, this lesson is already very good." Li Zheng nodded again and again.
"You are comfortable with this attitude..." Xie Qijun put down the draft paper and raised his hand. "OK, then according to what I said before, I finally came up with a question. If you can solve it, I will continue."
"please!"
"Just a simple fluid mechanics question, I will say it once, listen well--" Xie Qi raised his lips and smirked, "How much electricity can a drop of water carry?"
Li Zheng waited a long time in a daze, only to understand that he only laughed and didn't say anything, then he suddenly realized.
"that's it?"
"That's it." Xie Qi said, "You can set the conditions as you like. The cube can also be used for water droplets and spheres. It can be used with or without gravity. That's it."
"Ah." Li Zheng opened his mouth. "Yes..."
"What can I do, just count on you." After Xie Qi rubbed Li Zheng's head, he stepped out of the classroom.
When he turned back and closed the door, he was hitting Lu Yang.
"Teacher Xie, the lab is almost done. Amplifier go to dinner?"
"Well, let them go." Xie Qi leaned against the door of the classroom and waved casually.
"Don't you go?"
"I will wait."
"Oh..." Lu Yang glanced from the doors and windows, and it took a lot of effort to find Li Zheng in the back of the classroom. Then he was shocked, "Li Zheng is back?"
"Ok."
"Why not go to the laboratory?"
"Isn't that dissatisfied?" Xie Qi smiled and said, "Find me by name."
"Ah!" Lu Yang shivered and looked back into the classroom.
Full of regret and pity.
Why are you suffering, brother...
Teacher Xie's lesson is either a book or a crosstalk, is it not good to make good use of time?
"Although this kid doesn't agree with me, it's quite interesting." Xie Qi sighed and sighed in the glass. "Scientific research is the same, but I should like to see the wind more, but his way is also an article. Let's go."
"!" Lu Yang was another trembling, "Teacher Xie... are you praising him?"
"Don't you hear me think he's stupid?" Xie Qi said with a lip, "How can I teach high school students? Make him play, and he can't get out of the question to make him go home."
"Huh... that's right..." Lu Yang breathed a sigh of relief. "I said, you teach most people like the wind."
"That depends on the mood."
"Hehe..."
"I didn't think you were so punished before?"
"I will go now, this will go..."
...
In the classroom, Li Zheng took advantage of the surplus heat of the soaring state, there was no way to win, there was no way to win, and soon he sang out the idea of ​​understanding the question.
What is the maximum charge that a drop of water can carry?
Easily, he outlined a physical image in his mind.
First, there will be tension on the surface of the water droplets, causing the droplets to shrink.
The charge on the droplet surface expands due to repulsion.
When the repulsive force is equal to the tension, the water droplet will not maintain its shape and then breaks up.
At this time, the amount of charge that generates repulsion is the maximum amount of charge.
After figuring out the principle, Li Zheng took the pen and did it.
In the case of a vacuum without gravity, let the water droplets be spherical, radius r, density ρ, surface tension coefficient σ, the amount of charge carried Q, vacuum dielectric constant ε.
Then according to the "cutting analysis method" just learned, take a small micro element on the water drop to analyze the force...
Suddenly...
Slightly more...
No, draw a geometric figure...
Your mother, the curvature...
...
Appeared!
The tension is 2σ/r!
It must be right to be so handsome.
Then the repulsion...
Cut it into pieces and make it slightly up.
No matter, the differential in fluid mechanics is the sky.
Then calculate the electric field strength...
Hmm... I feel like Gauss's theorem is here...
So in the end...
The repulsion is 1/2·ε(Q/4πεr2) 2!
Make the repulsion and tension equal, solve the equation...
Appeared!
Q=8π√εr3σ!
To put it simply, when Li Zheng actually made it, he was already sweating a lot, and when he solved it, he just pinched the watch and pushed the door back to the classroom.
He walked all the way to Li Zheng, squinting and picked up the answer sheet.
Then he stared.
"I went to your mother, really made it?"
"Huh, isn't it difficult..." Li Zheng straightened out the hibiscus-like hair, "Can you start telling me about your research?"
"It's not...this..." Xie Qi searched for flaws for a long time without finding them, and scratched his head irritably. "I didn't finish the title, this is the first question."
"?!" Li Zheng got up in exasperation.
Damn you! Learning ruff!
"Don't worry, the second question is also very simple." Xie Qi placated, "Listen, second question-please use another method to solve the problem."
"???
"Open your mind, half an hour."
Xie Qifan closed the door again.
Li Zheng is not angry.
He can naturally go away.
But in that way, doesn't it make Xuepi cool?
No!
solution!
Hardware solutions!
So, for the first time, Li Zheng took his hatred to the head.
...
Half an hour later, Xie Qijun pinched the watch again into the classroom, rubbed his stomach and walked to Li Zheng's desk.
After picking up the paper, he jumped like thunder.
"Fuck!! Can you come up with this dumb thing?"
"Humph." Li Zheng wiped his head full of oil, and said with a sneer. "The principle of the least amount of action, the content of ordinary undergraduate mechanics."
"Third question!" Xie Qi flicked through the papers and said with a stern face, "Please come up with another solution."
"Ha...haha..." Li Zheng smiled abruptly, looking at the sunset outside the window, and slowly pulled out the hidden paper from the desk. "Sorry, I have already thought of this layer."
"?!" Xie Qi was shocked suddenly, and the whole person's world view was shaken.
He took the answer sheet stiffly, only glanced at it, and his hand fell down.
"This is the first question that forced me to apply the principle of virtual work." Li Zheng smiled and picked up the stationery. "I know, you don't want to teach me, just say, I'm going."
"You...you..." Xie Qi looked at the papers on the floor and scratched his scalp. "You beg me again... maybe I agreed..."
"Don't ask." Li Zheng carried his schoolbag, proud and arrogant.
How can I bow my head to Xuepi?
Xie Qi's face was crooked, avoiding this just look: "You, you just try to say two good things..."
Li Zheng frowned and said, "Smoking is harmful to health!"
"...Oh, seeing that you care so much about the teacher's body, I can barely teach you two lessons."
"..."
"Go for a walk, eat first." Xie Qi embraced Li Zheng and walked out. "You can probably understand my research at this level."
"To be clear, you must teach me."
"Hi, drink and talk."
"drink?"
"Let's go, let's go..." Xie Qi pushed Li Zheng and found a piece of paper stuck to his butt.
He twisted the paper and looked at it with a startled voice: "You have prepared a fourth solution??"
"Ashamed..." Li Zheng shouted and said, "This is the solution I got from asking outside, I can't understand it myself."
"It's right if you don't understand." Xie Qi photographed the paper and snorted. "The disturbance method is the Nobel Prize winner's method. Help your buddy check the papers, cheap!"
"Shut up!" Li Zheng was anxious.
"Ah?" After a while, Xie Qi slapped his head and quickly changed his mouth. "I understand, it's not a buddy, then she must have checked the paper, smart!"
"Ok."
...
Several kilometers away, Lin Yuejing yawned, threw away the scratch paper, and laid on the table.
This training seems quite interesting?