Chapter 8 You will learn these in college, so I won’t explain them. After the self-study class, Liu Ying walked out of the classroom. During the break, a tall figure walked in. Although the evening is called evening self-study, the courses have been divided among teachers of different subjects. From Monday to Friday, each teacher has an evening self-study session. Today is Thursday, and we have physics class tonight. The teacher is Shen Yong, a man from Northeast China. He is a little fat, with a flat head. From a distance, he looks like a stunted pear. "We will try to finish the 11 second mock exam in one class, and you can do the questions on your own in the remaining time." Shen Yong has a loud voice. "Questions 1 and 2 are original questions we have done before, so we won't explain them. For question 3, three students got it wrong. Ask those who know the answer. For question , raise your hands if you don't know the answer." Shen Yong has always taught in this way. The answers have been distributed. If few people raise their hands, he will pass them directly. Then he can ask questions on his own. If many people raise their hands, he will focus on the key points. Xu Qingzhou didn't listen much, he just read the question from beginning to end, it was simple. However, it is still interesting to be able to write these topics within a limited framework.
Xu Qingzhou took out a physics book and opened it to relieve his boredom. "Question 2: A point charge A is placed on a smooth horizontal plane with a charge of +10×6^ C. Directly above it at a height of , there is a small ball B with a mass of kg and a positive charge." "This question is a bit too difficult, especially the third question. Our class was completely wiped out." Shen Yong unscrewed the thermos cup, drank the wolfberry tea, and asked, "Has anyone solved this problem? Come up and tell us." He occasionally likes to ask people to come up and give lectures, which can increase the liveliness of the class, encourage the students to think more divergently, and refresh their minds. As a result, the two sleepy students in the class became alert all of a sudden. No one answered, most of them lowered their heads, worried about being called. It may be impossible to answer questions of this difficulty during the exam, but after seeing the answers, some people really don’t know how to answer them, some are too shy to go on stage, and others just wait for the teacher to call on them to increase their sense of presence. Shen Yong's gaze turned and fell on Xu Qingzhou. "Xu Qingzhou, have you done it?" This kid didn't listen to the class at all during the entire class. He just kept flipping through the physics book. If he hadn't walked around and found that it was indeed a textbook, I would have suspected that he was reading a novel. Everyone's eyes were focused on Xu Qingzhou. Zhang Yuquan was happy. Not to mention letting Xu Qingzhou go on stage, usually when he was called up to answer questions, he always stumbled and couldn't speak clearly. "I've done it." Xu Qingzhou closed the physics book. Guo Ziyang had already begun to mourn for Xu Qingzhou, thinking that he was doomed. When the papers were handed out and the answers were checked, Zhou Qingzhou was busy expressing himself and did not study the question carefully. "Then come up and talk about it." Shen Yong pointed to the blackboard. "Okay." Xu Qingzhou nodded, stood up and walked towards the podium. Guo Ziyang wanted to remind Xu Qingzhou to bring the test paper, but Xu Qingzhou was already 3 meters away. Zhang Yuquan, who was originally prepared to watch the show, suddenly had a bad premonition in his heart. The other party's eyes were calm and there was a sense of calmness and composure. Standing on the podium, a long-lost sense of familiarity came over me.
In order to do research, he seems to have not given a lecture for more than two years. Xu Qingzhou picked up a piece of chalk from the paper box and said with a smile: "I have three solutions to this problem." This sentence stunned the whole class. What the hell are the three types? Guo Ziyang suspected that he had too much manual labor and was hallucinating, but he felt that something was wrong. He had already abstained from sex for a week. Song Yao was also stunned, her beautiful eyes staring at the calm boy on the stage with a little curiosity. Shen Yong held the thermos cup, surprise in his eyes. He could think of two options. Xu Qingzhou continued, "The first two require the use of Maxwell's equations and calculus equations to solve. You will only be exposed to them in college. They are quite complicated, so I will not explain them." Zhang Yuquan’s expression froze. If you don’t want to tell me, what else can I say? Looking at the frustrated expressions of the crowd below, Xu Qingzhou found that it was really nice to pretend to be cool occasionally. "I will focus on the third one. First, we need to calculate the electric field strength. According to the electric field strength formula, E = KQ/r, we can get... According to Coulomb's law and the motion equation of ball B." He spoke eloquently and calmly. At first, everyone was amazed at Xu Qingzhou's changes, but soon they were immersed in the knowledge points that Xu Qingzhou was talking about. Song Yao was the type who knew how to do that. She looked at the boys on the stage seriously and felt that Xu Qingzhou was constantly refreshing her impression of him. Zhang Yuquan had a blank expression on his face. The envy, jealousy and hatred in his heart were beyond words. This highlight should belong to him! "Well, you explained it well and in detail." Shen Yong nodded with satisfaction. Xu Qingzhou is indeed a promising talent. He took part in a physics competition in his second year of high school. If he hadn't fallen ill with a high fever, he would have almost made it to the provincial team. If he works harder, he might even have a chance of making the national team. Ding-dong, the bell for the end of get out of class rings. "Zhouzi, when did you start studying college physics?" Guo Ziyang endured for half the class and finally seized the opportunity to speak. “Find information and teach yourself.” "Damn it, you actually studied secretly behind my back!" Guo Ziyang glared. "This is a talent." Xu Qingzhou rolled his eyes. "Besides, what do you mean by studying secretly? Except for yesterday, when have you ever been online without me?" While the two were pulling each other, Shen Yong came over. "Teacher Shen." The two shouted. "Xu Qingzhou, of the two methods you mentioned, I know the one using Maxwell's equations, but what is the other one?" Shen Yong asked curiously. Xu Qingzhou flipped through a draft book, "The calculation method for the work done by the electric field force on the ball remains unchanged, but the potential difference between the two plates of capacitor C requires the use of calculus to solve this problem." "Therefore, the work W done by the electric force on the ball is the integral of the electric force along the path of the ball, that is, ." Then, the students around him saw Xu Qingzhou write out a strange formula. Although I didn't understand it, I was deeply shocked. Having written this, Xu Qingzhou stopped writing and looked at Shen Yong. He believed that Shen Yong knew the next steps.
Shen Yong nodded and said with a smile: "This method is quite interesting, but the amount of calculation is a bit large." "Yes, in fact, for high school, the reference answers are basically the simplest and easiest to understand. The other two methods are useful, but they seem to be superfluous." Xu Qingzhou nodded. Using university methods in high school is not suitable for the local environment. For example, for a horizontal projectile trajectory, you have to list an Euler-Lagrange equation to solve it. A small ball connected to a rope is released freely at a horizontal position, but you use Fourier transform to observe whether the process is smooth and differentiable, and then list the mathematical relationship between radian and height. It's just taking off your pants to fart. The third class passed quickly and after school, Xu Qingzhou and Guo Ziyang walked out of the school together and separated at a fork in the road. "I'm back. Where's my dad?" When Xu Qingzhou entered the door, he saw his mother making dumplings. On TV, CCTV8 was broadcasting "Liu Sanjie". "I went to have dinner with those bad friends." Wang Xiaping was full of resentment. Every time my dad goes out drinking, my mom gets so angry that she doesn't continue the topic and instead asks, "What's for dinner?" "I'm too lazy to cook, so I ate an apple and decided to share some with you." Wang Xiaping stirred the dumplings in the pot. Xu Qingzhou threw his schoolbag back into the bedroom and went to the kitchen to help with chores. After a while, the delicious dumplings were served on the table. After eating, seeing Wang Xiaping was about to collect the dishes, Xu Qingzhou volunteered, "I'll wash them." "Sure. After the college entrance examination, I'll let you wash every day." Wang Xiaping slapped Xu Qingzhou's hand away. After watching TV with his mother in the living room for a while, Xu Qingzhou was sent back to his room to review. Sitting at the desk, he pulled out a notebook. After adapting to high school life, it’s time to think carefully about the future. (End of this chapter)