Chapter 780: There is also a third method (two/three)

Latest URL: This is a dream,
Xu Mang became the father of two children in his dream. The children are very smart, have good academic performance since childhood, and are very filial. After getting a scholarship every year, Xu Mang fell in love with the youngest son Xu Yang in high school and found a height. When he returned from the airport less than 1.5 meters away, Xu Mang was so angry that he vomited blood.
"Hey!"
"Professor Xie is calling you!"
"Wake up!"
Suddenly heard someone shouting to himself, Xu Mang opened his confused eyes, and saw a girl staring at him in front of him, and instantly fell into doubt. Does he have a relationship with her? But let's be honest... she looks average, not even a little bit worse than Xiaoman.
"what?"
"Who are you?" Xu Mang looked at her curiously. His face was filled with doubts and incomprehension about the situation in front of him. However, he soon discovered that something was wrong. The atmosphere in the entire classroom seemed to fall into silence. Look at yourself.
This...what the is this?
Why do you all care about me so suddenly? Could it be... the identity was revealed? glasses! Did you forget your glasses?
Xu Mang hurriedly touched his black-rimmed non-precision glasses, and the glasses were hung on his face. This was very strange. Although a pair of glasses could not change much, it did change his temperament and temperament. Changed... People changed accordingly.
"This classmate!"
"Have you already learned physics very well?" Professor Xie asked seriously: "Then solve the problem I just mentioned, two identical charged particles with a mass of m and a charge e, start to be apart Very far away, one particle is stationary, and the other moves towards a stationary particle at a velocity v and an aiming distance p equal to 2ke^2/mv^2."
"Then what's the neutral scattering angle of the center of mass system?" Professor Xie asked: "You answer."
what?
Particle system dynamics?
I didn't write this question.
Xu Mang recalled that when he wrote the dynamics of the particle system, he did not write any questions about the dynamics of the particle system. It is estimated that this topic was written temporarily by himself, but it is indeed a very good problem. It involves the translation of scattered particles. Reference frame and kinematic equation formula under the action of inverse square law force.
of course,
This is just one of the solutions. In fact, there are multiple solutions to this problem, each of which is different, but the answers are the same.
"Oh..."
"I... Am I going to the blackboard to write the process?" Xu Mang asked curiously.
"Correct!"
"Come to the blackboard to write." Professor Xie said seriously: "By the way... If you can't write this question, my basic physics course... You have to take it again. If your process and answers make me very Satisfied, my class does not need to come in the future, I will give you a full mark."
hiss!
Damn it!
Play such a big one?
Hearing Professor Xie’s words, many people in the room took a deep breath and didn’t feel scared, but it was more of a nostalgia for Xu Mang. He did not hesitate to use his own subject to verify the legend of a physics college. That is, don't talk back to Professor Xie, it's easy to walk around.
Xu Mang got up and walked through the crowd. Under the gaze of welcoming the heroes to the expedition, he went all the way to the blackboard. He silently wrote down Professor Xie’s questions before standing in front of the blackboard, looking at the topic in front of him. Somewhat dazed.
like...
The blackboard is not enough!
"Ahem!"
"Professor Xie?"
"What should I do if the blackboard is not enough?" Xu Mang asked cautiously: "These four large blackboards are not enough for me to write...What if the writing is broken in the middle?"
Professor Xie frowned, his eyes full of doubts, and said seriously: "Impossible! This is my topic. Let alone four blackboards, two blackboards are enough. Anyway, write it... Tell me if you don’t stop, today’s class won’t take place, it all depends on how you solve the problem.
"..."
"Oh!" Xu Mang nodded, and reluctantly picked up the chalk on hand, and wrote a word ‘solution’ in a steadily skinny manner, feeling a little twisted, and hurriedly added a colon to feel comfortable...
have to say,
I am used to writing essays and then go back to solving such common topics.
original,
No one was optimistic about Xu Mang, including Professor Xie. However, when Xu Mang came up with a calculation process based on the scattering particle translational reference frame, Professor Xie realized that things were not as simple as he thought.
Immediately after,
Professor Xie saw the calculation process of the kinematic equation formula under the action of a very perfect inverse square law force, and he could not help being surprised. However, the surprised expression remained very short, and soon returned to normal, which would scatter the particle translational reference frame. , And the kinematic equation formula under the action of the inverse square law force, can not explain what the problem is.
The real difficulty lies in the back. It is necessary to draw a flat two-dimensional diagram and calculate the subsequent process based on the two-dimensional diagram.
Swish,
Xu Mang continued to solve the problem, but his speed was somewhat slow.
and many more!
When Professor Xie saw Xu Mang writing a set of relations, m1 and m2 were the masses of scattered particles and scattered particles respectively. When m1=m2=m, his expression gradually changed from cold to a little panic. As expected...he saw Xu Mang. Imagine a particle group relationship.
Suppose the velocities of particles 1 and 2 relative to the center of mass translation reference frame are v1c and v2c, respectively, parallel and opposite, because m1=m2=m, v1c=v2c, vr=v1c-(-v2c)=v1c+v2c=2v1c.
This...
This student... not easy!
Have you already learned all the content in advance?
at the same time,
The students in the audience were a little shocked. They never thought that the players who were considered to be the Bronze Rank were turned into the King Rank, especially the two girls who sat in front of Xu Mang.
"he..."
"so amazing!"
"Is this guy pretending to be a pig and eating a tiger?" The girl who had awakened Xu Mang said to her best friend: "Beijing University...it's like a place where a tiger, a dragon, and a tiger hide."
"I just said... the more you don't seem to care, the more likely you are to be a peerless genius." The girlfriend laughed and said, "Are you still questioning what I said? He must be a genius... From that decadent energy, it's not a genius... God doesn't agree."
"cut!"
"I retort!"
"Professor Xu from Fuda is not the kind of person you mentioned." The girl said disdainfully: "Professor Xu is a genius among geniuses, but at the same time he works very, very hard. I think... genius and hard work. It will always be hooked up."
at this time,
Xu Mang’s problem-solving process is still going on, but it’s about to come to an end. However, in just ten minutes, Xu Mang has conquered everyone present, including Professor Xie standing on the side. He couldn’t think of it. A student exists.
perfect!
so perfect!
It was exactly the same as his own answer, not even a symbol was wrong.
Professor Xie saw that Xu Mang had solved his problem smoothly and couldn't help but say: "Okay! What this colleague did..."
Halfway through,
Xu Mang came to the two blackboards that could be moved up and down, and continued to write about the problem-solving process, but his weird behavior made many people feel a little confused. He clearly solved the problem. Why is he still writing?
This...
What is this doing?
Professor Xie was about to open his mouth to speak, but the next second he spoke, he abruptly held back.
Centroid translational reference frame?
this is...
The second solution?
Professor Xie froze for a moment. There is indeed a second solution, and it is very convenient, but it is not suitable for freshmen, he... how could he?
impossible!
at this time,
Professor Xie became more and more curious about this student. He stimulated himself again and again, refreshing his understanding of the freshmen. Is he really a freshman? Or was it a big three or four or a graduate student came to make trouble?
three minutes,
All the students present witnessed the birth of a miracle. Professor Xie’s question seemed to have two completely different solutions, and the person who did this turned out to be the bronze contestant who slept in class before.
"I rely on..."
"Who is this guy? Why haven't I seen it?" A student in the room asked with a puzzled face: "Have you seen him? Wearing such earthy glasses... there is no trace of young people at all. , And...how do I look at his lazy look, how do I change my heart."
"Yes indeed!"
"But they are better than us." The boy on the side sighed: "The pressure is so great... If I had the same talent as Professor Xu, that would be great."
"Ha ha!"
"You're thinking about fart!" The boy ridiculed, and then continued to look at the blackboard. During the second problem-solving process, he looked at the problem and found the problem. The boy suddenly felt the back of the answering student. Where have you seen it.
This back...
So familiar!
"..."
"Did I have hallucinations?" The boy said cautiously: "I...I think his back looks a bit like Professor Xu!"
"You bullshit!"
"Before, you thought that your girlfriend had memorialized a certain female celebrity. It was because of this relationship that she was with others. I saw...like a fart!" The boy next to him said angrily, "Xu The professor is busy, how could he be so boring? People have everything to do!"
"Yes!"
After a few more minutes,
Xu Mang has completed the second problem-solving process, but the space left for him is only one-half of a blackboard~EbookFREE.me~What should I do?
How should the third approach appear?
For a while,
Xu Mang stood there stupidly, not knowing what to do.
At this time, Xu Mang was in the mood, and finally had a feeling of youth, but this feeling was too short, not even half an hour.
"This classmate!"
"You are very good!" Professor Xie smiled with satisfaction and said to Xu Mang: "You are far beyond my expectation. These two methods can be mastered at the same time. It's not easy... and it doesn't make the whole process muddled. Nothing is superfluous, not bad, good, good!"
Xu Mang shrank his neck and said cautiously: "There is a third way to solve the problem... but I can't write it anymore."
......