Inside Wu Gang's room, five minutes ago.

Wu Gang held a backpack in his hand, unzipped it familiarly, and said: "Brother Liu Hai, let me tell you, I have long heard my mother and Aunt Liu say that your grades are very good, not only in the top class, but also in this college entrance examination." You're better than me when you get a small grade, and I've long wanted you to tutor me, but I've never been embarrassed to speak. ”

"Now it's okay, with Brother Liu Hai to help me, my grades will definitely rise to the top, even if it is Class 3, I'm afraid it can't be as good as Brother Liu Hai personally teaching me. Hehe, I've made a lot of money this time, Brother Liu, thank you very much. ”

Wu Gang's face was full of joy and a little flattery.

The bangs are about 1.7 meters tall, slightly lower than Wu Gang's half a head, slightly chubby face, and a small flat head on the top of his head, which looks particularly neat.

The upper body is an Adidas shirt that I just bought, but it looks a little awkward due to some fat figure, and the knee-high shorts underneath seem to be new.

Hearing Wu Gang's flattery, Liu Hai didn't want to shake off anything, and said modestly with a chuckle: "That's all Aunt Wu and my mother talking nonsense, how can my grades be so good? This college entrance examination is just a little luckier. ”

Liu Hai said this, with a little pride on his face, and said seriously: "But Gangzi, you Brother Hai still have to persuade you, this study, you must be serious, and you must have a good attitude, you heard Aunt Wu say that your foundation is not very good, I think you must first thoroughly understand the basic knowledge in the books, but also master certain learning methods, don't live up to Aunt Wu's expectations of you." ”

After finishing speaking, Liu Hai continued: "Let's talk about learning methods later, even if I sue you now, if the basic knowledge is not solid, it will be completely useless." By the way, didn't you say that there are a few questions, show them to me, I will teach you some ways to solve the problems first, and then I will slowly consolidate the basic knowledge for you when I have time later. ”

Wu Gang had already taken out the book from his schoolbag at this time, and when he took out the schoolbag, he had already flipped the book to the bookmark he had folded.

Then Wu Gang frowned and said, "I only started reading this book tonight, and I didn't understand much about the last few questions." ”

While speaking, Wu Gang pointed to the title and handed the book to Liu Hai.

Liu Hai's chest straightened slightly, and after stroking his eyes, he confidently took the book handed over by Wu Gang, and then swept towards the few topics that Wu Gang pointed to, while taking the book, he said in a teaching tone: "You are a physics problem, the most important thing in physics is the model, for example, if you look at the first question, this question is to be used!"

Ga!

At this point, Bang Hai's words stopped as if they were mechanically stuck.

It seems that I can't go on.

Immediately, Liu Hai felt a little embarrassed, and then picked up the book with both hands at the same time and slowly read the first question.

"A slender glass tube with a uniform inner diameter and open at both ends, inserted vertically into the water, part of the tube on the surface of the water. Now seal the upper end of the tube with your fingers, seal a certain amount of air in the glass tube, and express its volume by V0; then lift the glass tube to the water surface along the vertical direction, and set the volume of gas sealed in the glass tube to V1 at this time; finally turn the glass tube 90 degrees in the vertical plane, let the glass tube be in a horizontal position, and set the volume of gas sealed in the glass tube at this time to be V2. Yes. ”

Reading this, Bang Hai's pupils shrank slightly, and a trace of imperceptible panic flashed.

Obviously, he had never done such a problem, and in his own image, there were no similar problems and formulas.

"Well, this question is relatively novel and difficult, I can't solve it for a while, and it's a waste of time, so I'll think about it when I go back. I'll give you an answer tomorrow. Let's take a look at the next one. Bangs said a little embarrassed, and then continued to read the question: "The following question is like this. ”

"A whiteboard long enough, on a level tabletop, at rest. A block of graphite (which can be thought of as a particle) rests on the whiteboard. There is friction between the graphite block and the whiteboard, and the sliding friction coefficient is μ. Suddenly, the whiteboard moves in a constant linear motion at a constant speed, and the graphite block will mark black marks on the board. After a certain period of time, the whiteboard suddenly stops and no longer moves. At the end of the graphite block, when the block is no longer moving, the length of the black marks on the whiteboard may be ?" (the acceleration due to gravity is known to be g, not counting the mass lost during the graphite-plate friction scratch)"

"This question is simple, as long as, as long as?" At first glance, Liu Hai immediately made a conclusion, because he had done similar questions, and the model was relatively simple.

However, after he only needed two sentences, he immediately paused again, because this question was not as simple as he imagined. First of all, the final velocity of the ink block when the whiteboard stops is not clear, and it can be divided into several categories.

In an instant, the bangs were not good. After only two sounds, he immediately stopped talking, and then, he immediately continued to look at the following questions, and immediately, his whole face was extremely dark.

Then, Liu Hai, who found that something was wrong, closed the book and looked at a few big words on the book cover: "High School Students Physics Competition Tutoring!" In an instant, Liu Hai's whole face flashed with anger: "Wu Gang, you deliberately tricked me? This is obviously the topic of the Physics Olympiad! You tell me that you see this?"

Wu Gang watched a series of movements of bangs lightly on the side, and finally changed his previous flattery, and said calmly: "Brother bangs, in fact, I heard everything you and Aunt Liu said before. For the sake of you and me, I don't want to slap you in the face in front of adults, and I don't want to embarrass Aunt Liu. You're a smart guy too, you understand what I'm saying, right?"

Wu Gang's tone was very calm, and he was telling the truth, the friendship between the Liu family and the Wu family in the past was indeed good.

Liu Hai's expression froze, his face was a little red, and he sneered with annoyance: "Wu Gang, what do you mean by this? What are you dragging with me on your grades? You think you are a cow if you take a book of physics Olympiad, right? I sue you, with your attitude and foundation, even if you beg me to help you with your tuition, I am reluctant." ”

The taste of being slapped in the face on the spot was very uncomfortable, not to mention Wu Gang, who had always been ignored by him? bangs immediately became angry.

"The answer to the first question you read is A, the answer to the second question is AC, and the answer to the third question is B. Wu Gang replied unhurriedly, then took out a draft book from his schoolbag, turned the last page and handed it over, and continued: "Of course, you can also think that I have read the reference answer in advance, this is my derivation process, it is not on the reference answer, you can see if there is any mistake?"

Bangs immediately flipped to the page where the reference answer was located, and then compared it with the scratch paper handed over by Wu Gang, the whole person was stunned, and his expression changed I don't know how many times, and then he said: "You!~Impossible!~ The changes of these formulas have not been learned in high school!~"

"It can't be my business, Brother Liu Hai, you're a smart person. If you feel hungry, finish your late night snack before leaving. If you want to continue to pretend that you are the most hanged in front of my parents, whatever you want. When the time comes, I won't have such a good temper. Wu Gang's tone was flat again, and then he retreated the door.

With a smile on his face, he walked out with bangs in his arms. "Brother bangs, what did I say, I said that we will have dumplings to eat as soon as we come out, are you right?" Wu Gang let go of his bangs and ran to the table, his face was as usual.