This is a dream,

Xu Mang became the father of two children in his dream. The children were very smart, had good academic performance since childhood, and were very filial. He received scholarships every year. However, in high school, his younger son Xu Yang fell in love and also found a height.

After returning from the airport, which was less than 1.5 meters tall, Xu Mang was so angry that he vomited blood.

"Hello!"

"Professor Xie is calling you!"

"Wake up!"

Suddenly he heard someone calling him. Xu Mang opened his confused eyes and found that there was a girl in front of him staring at him. He was instantly confused. Did he interact with her? But to be honest...she

He looks average, just a little bit worse than Xiaoman.

"ah?"

"Who are you?" Xu Mang looked at her curiously, his face full of doubts and confusion about the situation at hand. However, he soon discovered that something was wrong. The atmosphere in the entire classroom seemed to fall into silence, and everyone around him was confused.

Look at yourself.

This...what exactly is going on?

Why are everyone so concerned about me all of a sudden? Has... my identity been exposed? Glasses! Did you forget to bring your glasses?

Xu Mang hurriedly touched his black-framed non-prescription glasses, and the glasses hung on his face. This was very strange. Although a pair of glasses couldn't change anything, it did change his temperament.

As things change... people also change.

"This classmate!"

"Have you learned physics very well?" Professor Xie asked seriously: "Then let's solve the problem I just mentioned. Two identical charged particles with mass m and charge e begin to be separated from each other.

Very far away, one particle is stationary, and the other is moving towards the stationary particle at a speed v and an aiming distance p equal to 2ke^2/mv^2."

"So what is the neutralization scattering angle in the center-of-mass system?" Professor Xie asked, "Please answer."

ah?

Particle system mechanics?

I didn’t write about this question.

Xu Mang recalled that when he wrote the dynamics of particle systems, he did not write any questions about the dynamics of particle systems. He probably wrote this topic temporarily by himself, but it is indeed a very good question, and it involves the translation of scattered particles.

Reference system, and kinematic equation formula under the action of inverse square law force.

certainly,

This is just one of the solutions. In fact, there are many solutions to this problem. Each solution is different, but the answers obtained are similar.

"oh..."

"I...am I going to the blackboard to write down the process?" Xu Mang asked curiously.

"right!"

"Come to the blackboard and write." Professor Xie said seriously: "By the way... If you can't write this question, my basic physics course... you have to retake it. If your process and answers make me very satisfied

If you are satisfied, you don’t need to come to my classes in the future, and I will give you a perfect score.”

hiss!

Damn it!

Playing such a big game?

Hearing Professor Xie's words, many people present took a breath and tried not to be frightened. However, it was more of a remembrance of Xu Mang. He did not hesitate to use his own failure to verify a legend in the School of Physics.

That is, don't talk back to Professor Xie, as it's easy to walk around without food.

Xu Mang stood up and walked through the crowd. Under the eyes of everyone welcoming the heroes on the expedition, he came all the way to the blackboard. He silently wrote down Professor Xie's previous question. Then he stood in front of the blackboard and looked at the topic in front of him.

Somewhat dazed.

like...

There are not enough blackboards!

"Ahem!"

"Professor Xie?"

"What should I do if the blackboard is not enough?" Xu Mang asked cautiously: "These four big blackboards are not enough for me to write on... What if the writing is broken in the middle?"

Professor Xie frowned, his eyes full of doubts, and said seriously: "Impossible! This is a question I asked. Not to mention four blackboards, two blackboards are enough. Anyway, just write...write

If you can't stand it anymore, tell me and I won't have class today. It all depends on how you solve the problem."

"..."

"Oh!" Xu Mang nodded, helplessly picked up the chalk at hand, and wrote the word "Jie" steadily and smoothly. He felt a little distorted, so he hurriedly added a colon and felt better...

I have to say,

I'm used to writing essays, and it's hard to get used to it when I go back to solve such ordinary questions.

original,

Everyone was not optimistic about Xu Mang, including Professor Xie. However, when Xu Mang derived a calculation process based on the translational reference system of the scattered particles, Professor Xie discovered that things were not as simple as he thought.

Immediately afterwards,

Professor Xie saw a very perfect calculation process of the kinematic equation formula under the action of the inverse square law force. He couldn't help but show a hint of surprise. However, the surprised expression lasted for a short time and soon returned to normal. The scattering particle translation reference system

, and the kinematic equation formula under the action of the inverse square law force cannot explain anything.

The real difficulty comes later. You need to draw a two-dimensional planar diagram and calculate the subsequent process based on the two-dimensional diagram.

Swish, swish, swish,

Xu Mang continued to solve the problem, but the speed was a little slow.

etc!

When Professor Xie saw Xu Mang writing a set of relationships, m1 and m2 were the masses of the scattered particles and the scattered particles respectively, m1=m2=m, his expression gradually changed from indifferent to a little panicked. As expected...he saw Xu Mang

Imagine a particle group relationship.

Assume that the velocities of particles 1 and 2 relative to the center of mass translation reference system are v1c and v2c respectively, parallel and opposite, because m1=m2=m, v1c=v2c, vr=v1c-(-v2c)=v1c+v2c=2v1c.

this...

This student... is not simple!

Have you already learned all the content in advance?

at the same time,

The students in the audience were a little shocked. They never expected that the player who was originally considered to be a bronze player would become a king player, especially the two girls who were sitting in front of Xu Mang.

"he..."

"That's awesome!"

"Is this guy pretending to be a pig and eating the tiger?" The girl who originally woke Xu Mang said to her best friend: "Peking University... is simply a place like Crouching Tiger, Hidden Dragon."

"I just said it...the more someone seems to not care, the more likely he is a genius." The best friend said with a smile: "Are you still questioning my words now? He must be a genius...just

From that decadent energy, even if you are not a genius... God will not agree to it."

"cut!"

"I object!"

"Professor Xu from Fuda is not the kind of person you said." The girl said disdainfully: "Professor Xu is a genius among geniuses, but at the same time he works very hard. I think...genius and hard work

It’s always hooked.”

at this time,

Xu Mang's problem-solving process is still going on, but it is coming to an end. However, in just ten minutes, Xu Mang has conquered everyone present, including Professor Xie standing next to him. He never imagined that such a thing would happen.

A student exists.

Perfect!

So perfect!

It turned out to be exactly the same as my own answer, not even a single symbol was wrong.

When Professor Xie saw that Xu Mang had solved his problem smoothly, he couldn't help but said, "Okay! This colleague has done a great job..."

Halfway through the words,

Xu Mang came to the two blackboards on the side that could be moved up and down, and continued to write down the problem-solving process. However, his weird behavior made many people a little confused. He had obviously solved the problem, so why was he still writing?

this...

What is this doing?

Professor Xie was about to open his mouth to speak, but the next second the words reached his lips, he held them back.

Center of mass translational reference frame?
To be continued...