Into Unscientific

Chapter 549: Mr. Xu's small class starts (Part 2)

Chapter 549 Mr. Xu’s small class starts (Part 2)

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In the house.

Zheng Tao finished speaking.

At the scene of the interest group, where there were not many chattering noises, the quietness dropped a lot again.

It is clear.

After all, this is the first gathering of everyone, and most of the members are quite restrained, not daring to speak easily.

See this scenario.

Zheng Tao didn't feel disappointed or surprised, but smiled at everyone as usual:

"Comrades, we are all old acquaintances who have known each other for a while, so there is no need to be so lucky?"

"The main purpose of our group is that everyone can speak freely, regardless of hierarchy, just like everyone did in school back then. There is no need to have too much psychological pressure."

"How about it, is there any comrade who volunteered to fire the first shot?"

Say it.

Zheng Tao turned his head and winked at a girl sitting in the corner calmly.

This is a babysitter arranged by Zheng Tao in advance. In order to avoid being neglected, Zheng Tao also specially chose a female comrade.

But just as this Thor was about to appear on the stage.

At the diagonally opposite corner of Zheng Tao's seat.

A boy who wears glasses and has a single ponytail behind his head, who looks a bit literary, raised his hand first:

"Comrade Zheng Tao, then I will have the audacity to be a stepping stone and give everyone a head start."

Zheng Tao was slightly taken aback, and soon his face brightened:

"No problem, no problem, Comrade Fang Zhong, if you have any questions, just ask, let's work together."

to be honest.

Zheng Tao was indeed a little surprised.

At first, he thought that someone would take the bait only if the babysitter he had arranged appeared on the stage, but he didn't expect someone to jump out on his own initiative.

It’s like fishing guys are ready to buy fish in the market, but one fish automatically jumps into the net.

This is really

Very good.

As for the boy who spoke, Zheng Tao also knew him.

This person is called Fang Zhong, who graduated from the well-known South China Institute of Technology, which is later known as South China University of Technology.

Fang Zhong is not only highly educated, but also very good at the melodica. Every time the educated youths of the base hold various gatherings, the organizers basically ask him to help with the accompaniment.

Then a group of male singles sat by the bonfire, thinking about the beauty of love in the melodious harmonica, and then continued to be single the next day.

The line of sight returns to reality.

I don’t know if it’s due to the long-term experience of ‘performance’.

Fang Zhong looked very calm under the gaze of the crowd at this time, quite like a social cow.

I saw him adjust his glasses, cough lightly, and said:

"Comrades, the problem I want to share with you is actually a phenomenon I discovered at work a few days ago."

"As you all know, I am currently assigned to work in the literary sideline team of the base, mainly to help the team."

"Recently, the sideline team is making stage preparations for the stage commendation meeting in the factory. In addition to banners, the stage will also hang a few rows of small balloons to enliven the atmosphere."

"About three days ago at noon, when I was blowing up the balloon, I suddenly discovered a situation, that is, the balloon will be more laborious at the beginning, but it will become easier and easier later on."

Speaking of which.

Fang Zhong couldn't help but rubbed his temples, sighed and said:

"I am a person who likes to be serious. When I encounter this situation, I suddenly want to understand its principle."

"So I have been thinking about this question for the past few days. What is the reason or principle that caused this situation?"

"But after thinking about it, I couldn't figure out why."

“.”

Fang Zhong’s reputation and popularity in the youth circle of the base are very good, otherwise he would not have the confidence to say such things [presumably everyone knows].

In addition, the question he asked was indeed a little new, and it was a small detail that many people didn't pay attention to at all.

So fast.

There was a low voice of discussion in the room.

After a while.

A tall, thin, sallow-faced, malnourished boy raised his hand:

"Comrade Fang Zhong, could it be your illusion?"

"After all, according to the gas pressure formula pV=nRT, it seems that what you said should not happen."

Heard what the tall and thin boy said.

Several people at the scene nodded in agreement.

Gas pressure formula pV=nRT, this is a concept that is widely popular even in this era—relative to the level of college students.

According to the formula, it is not difficult to judge that the more gas the balloon is, the harder it is to blow.

However, Fang Zhong was silent for a moment when he heard the words, and shook his head resolutely:

"It should not be my illusion, because I also asked several comrades who blew up balloons together, and everyone also said that this was the case."

"That is, the bigger the balloon is blown, the easier it will be to blow up."

Say it.

Fang Zhong also took out a small balloon that was not blown up from his body, and threw it in front of the boy precisely:

"Comrade, this is the little balloon my team leader gave me after I worked overtime yesterday. You can try blowing it up."

“.”

The tall and thin boy looked up at Fang Zhong, picked up the small balloon, put it to his mouth and blew it.

inhale,

exhale,

Phew.

The balloon soon began to grow slowly.

And just when the balloon swelled to the size of a grapefruit, the tall and thin boy's eyes suddenly showed a hint of consternation.

Then he continued to blow two more times, and the balloon eventually became about the size of a basketball.

Then the tall and thin boy slowly opened his mouth, holding the balloon with both hands, letting the gas in it puff out.

See this scenario.

Fang Zhong couldn't help asking him:

"How is it? Is what I said correct?"

The tall and thin boy nodded silently.

During his attempt just now, what Fang Zhong said did happen.

That is, there was obvious resistance at the beginning, but the bigger the balloon, the easier it is.

Subsequently, several boys around him also tried it one after another, and they all found that the insufflation resistance of the balloon at the beginning is much higher than that in the middle and late stages.

And this is obviously a counterintuitive situation, so these educated youths on the scene immediately had a desire to discuss.

"That... I have a guess."

The person who raised his hand this time is a future boss, that is, Yang Fujia, who Xu Yun recognized before, a famous atomic energy scientist in the future:

"Could it be that the wall layer is thicker and relatively compact when the balloon is not blown up, but becomes thinner and looser after blowing up, so it becomes easier to blow up?"

Hear this statement.

Zhou Shaoping, who sat across from him, thought for a moment, then quickly shook his head:

"Lao Yang, your explanation is too life-like, and it is far away from the essence of physics."

"I think if this phenomenon does exist, then it must have a deeper explanation. After all, everything is about science."

Xu Yun glanced at Zhou Shaoping.

Due to the problem of equipment accuracy, the physics community in this period has not yet developed the understanding of the microscopic field to the next level.

Therefore, most physicists firmly believe that everything can be answered through existing theories—especially the new generation of domestic physicists such as Zhou Shaoping and others.

This kind of cognition will continue until Gell-Mann proposes the quark model, and the physics community will find that they are not only a pile of dark clouds above their heads, but also the ground under their feet is illusory.

Of course.

It has not been a few years since Gell-Mann proposed the quark model, so in the theoretical physics circle of later generations, there is a very interesting nickname for the physicists of this period:

The last Candide.

Immediately after.

Several members have put forward their views:

"Could it be a problem of tension? The surface of the balloon is deformed, so the tension changes?"

"It definitely has something to do with the tension, but what about other values? - Don't forget, the balloon will fly around when it is deflated, and there is usually a sense of sprinting at the end, which means that the ratio of tension to something must be constant of."

"Will it have something to do with air resistance?"

"I think it has something to do with gravity."

The discussion became more active as the atmosphere at the scene became more active. In the end, even Zheng Tao and Lin Yu also made some analysis.

But after several discussions.

In addition to confirming that the situation should be related to tension, the rest of the guesses and judgments were quickly rejected one after another.

As a result, we chatted and chatted.

Just when everyone was a little stuck, a sentence suddenly sounded from somewhere on the table:

"Comrade advisor, why have you been silent? Do you understand the cause of this situation?"

Among them, the word "consultant" has been amplified.

As soon as the words came out.

The originally lively scene suddenly became silent.

唰—

Everyone's eyes locked on Xu Yun who was sitting in the wheelchair again.

The person who spoke cannot be said to be hostile or have ulterior motives, but it is obvious that he is not convinced by Xu Yun's title of 'consultant'.

See this scenario.

Zheng Tao couldn't help but cast a concerned and questioning look at Xu Yun, which meant clearly:

Can you do it?

Xu Yun replied to him with a hint of 【Don't worry】.

Then he turned around and looked at the crowd, and said concisely:

"To tell you the truth, I am lucky enough to know this truth."

“.”

No one made a sound at the scene, but the pupils of some members shrank slightly, looking quite surprised.

To know.

Except Bao Zheng.

Although the current members are all under 30 years old, all of them are basically graduates from prestigious schools, and there are as many as four international students—this still excludes the numbers of Xu Yun and Lin Yu.

In the eyes of most people.

Comparing them one by one, there may be a gap in ability between them and Xu Yun.

After all, many of them had understood the principle of the damper in advance, and they thought that there was probably a gap in knowledge between Xu Yun and Li Jue and the others who asked them to keep the matter of the weather Doppler radar a secret.

But on the other hand.

This gap is not so outrageous that all the people together are inferior to Xu Yun alone, and the three cobblers can match Zhuge Liang at any rate.

Of course.

A large part of the reason for this kind of psychology is also because Xu Yun's age doesn't look too old.

If it were a young man in his fifties or sixties, everyone's attitudes would not be so complicated.

Seeing Xu Yun express that he knew the truth, Fang Zhong hurriedly asked:

"Comrade consultant, can I trouble you to explain the principle of this matter?"

"To tell you the truth, this problem has troubled me for more than three days, and I have to think about it for an hour or two every night before I can fall asleep."

Xu Yun glanced at this cool handsome guy, and did not directly explain the principle, but asked him:

"Comrade Fang Fangzhong, right?"

"Before explaining the principle, I want to ask you a question."

Say it.

Xu Yun pointed to the deflated balloon on the table, and said:

"Suppose there are nine such small balloons and one large balloon in front of us, and they have the same volume, who can store more gas?"

"Is it a small balloon? Is it a big balloon? Or are there as many?"

Hear this statement.

Qiao Caihong, behind Xu Yun, blinked and subconsciously said:

"Comrade Han Li, do you need to ask? Of course it's the same amount."

"No!"

As soon as Qiao Caihong finished speaking, Lin Yu on the other side shook his head:

"No, this question is not that simple."

"Nine small balloons and one big balloon have the same volume as V, but it doesn't mean that their pressures are the same."

"According to pV=nRT, it can be clearly seen that once the pressure is different, the stored gas will also be different."

A question mark immediately appeared on Qiao Caihong's face:

"OvO?"

Xu Yun smiled at the silly girl, then looked at Lin Yu on the right, and affirmed:

"Comrade Lin Yu is right, this problem is far more complicated than it seems."

"Then Comrade Lin Yu, can you analyze the difference in pressure between the big balloon and the small balloon?"

Lin Yu thought for a moment, frowned and shook his head gently:

"Intuition and logic tell me that the pressure of the big balloon must be stronger, but I don't know the principle."

Xu Yun cast an approving look at the girl.

Which pressure is stronger, the big balloon or the small balloon.

This issue will be left to later generations, and many people will definitely say it is a big balloon.

The reason is that the contraction force of the balloon membrane can be regarded as a spring system, and then a qualitative analysis can be done directly.

But in fact.

This question is far from simple.

Indeed.

Naturally, the tension σ should increase with the size of the balloon, that is, the increase of the deformation.

Don't forget.

As the balloon expands, 1/r decreases as the size of the balloon increases.

So if you analyze from the material level, you must build a non-qualitative model.

This involves the hyperelastic constitutive of rubber, which must be applied to a generalized hyperelastic model like the Ogden model.

But students who have studied thermodynamics in later generations should know it.

This problem has a more acceptable physical analysis method besides the non-directional model of the material.

Think here.

Xu Yun organized some words and said to everyone:

"The difference between a small balloon and a big balloon lies in their size. When the balloon expands, its surface will start to become tighter and tighter, and there is always a tendency to shrink back."

"If the pressure of the gas inside the balloon was the same as the pressure of the gas outside the balloon, there would be no other force that could balance the resilience of this balloon skin."

"So the gas pressure inside the balloon is actually higher than the outside of the balloon, or the resilience of the balloon skin compresses the gas inside the balloon."

Speaking of which.

Xu Yun asked Qiao Caihong to push the wheelchair to the edge of a blackboard, picked up chalk and drew a picture.

The shape of the schematic diagram is very simple, and the intuitive description is just that.

Give a "yeah" gesture, then face left horizontally, with an arrow on each fingertip of the two fingers.

Then Xu Yun wrote an O at the intersection of the "fingers", and wrote an A in the middle of the arc connecting the fingertips:

"Look, everyone, the point O here is inside the balloon, and A represents a very small square on the surface of the balloon."

"Because the balloon is inflated, the surface is not flat but has a curved curvature."

"The surface tension T is trying to flatten this arc as much as possible."

"In this way, isn't it obvious?"

See this scenario.

Many members nodded subconsciously.

really.

There is a curvature on the surface of the balloon, which is an expression that elementary school students can understand.

So although the direction of the surface tension in the diagram is perpendicular to the radius R, it is not perpendicular to the connecting line from the center O of the sphere to the central point A of this small area.

If there is no other force at this time, the film, that is, the surface of the balloon, will naturally be unable to maintain balance.

In other words.

There must be a pressure difference on both sides of the balloon skin to offset the force of the surface tension T on the line OA.

Then Xu Yun wrote another derivation:

detF=λ1λ2λ3=1, where λi (i=1, 2, 3) represents the stretch ratio along three orthogonal directions.

Ψ=∑p=1Nμpαp(λ1αp+λ2αp+λ3αp3).

When p=1, α1=1.

Write Ψ=2μ(λ1+λ2+λ33).

Assume that the balloon on the curved surface belongs to the state of equal force in two directions, and is free in the x3 direction.

The Cauchy stress is written as σ3=P+∑p=1Nμpλ2αp=0. (Note: I'm not sure if the Cauchy stress has a fixed formula at this time, let's take it as it is, after all, this plot is very important)

Assume that the balloon has an initial radius R and an initial wall thickness H. After deformation, the radius is r and the wall thickness is h.

Then the final formula is:

p=2σhr=2λ3σHR=2HR∑p=1Nμp(λαp3λ2αp3).

This time.

More people at the scene showed enlightenment on their faces.

It is not difficult to see from this formula.

The volume element δl/Rl is in the middle of the formula, that is to say, no matter what the value of x, t, ya, etc. is, δl/R remains unchanged.

In other words.

At this time, divide both sides of the equation by δl with the specific value, and then substitute into pV=nRT.

will find

P=T/R will first decrease and then increase.

Write here.

Xu Yun put down his pen, spread his hands, and said to everyone:

"Then the answer is obvious."

"As the volume of the balloon increases, the air pressure inside does not increase or decrease blindly."

"Its trend is to decrease first and then increase, which is called extreme point instability."

"When the air pressure decreases, it will be more difficult for us to blow up the balloon."

"When it exceeds the extreme point and becomes a 'big balloon', the internal pressure increases, and it will naturally be much easier to blow up—the internal pressure is strong, and the 'pressure' applied to the rubber will be greater."

Due to the blocking of the bandage.

Therefore, everyone at the scene did not realize that when Xu Yun said these words, his expression was actually not very confident.

no way.

Let’s not talk about the neo-Hookean model these days, even the Varga model hasn’t come out yet.

Without model derivation, Xu Yun’s famous 1.4 radius ratio cannot be proved.

So he can only find another way to prove it with the angle of three-parameter degrees of freedom.

Anyway, there is nothing wrong with the value

And just after Xu Yun finished explaining.

The entire study group was silent for a moment, and then burst into applause.

Papapa—

The expressions of everyone were not excited, but most of the doubts in their eyes dissipated.

Instead, it is goodwill and recognition.

It's just like.

Xu Yun changed from a sacrificial offering to a church member?

See this scenario.

Xu Yun couldn't help but heaved a sigh of relief.

Fortunately, the first level was finally passed smoothly.

Mentioned earlier.

After meeting Zhou Shaoping, Xu Yun came up with the idea of forming an interest group.

It’s just that Xu Yun’s original plan was to figure it out slowly, and then do these things after he has established a firm foothold in the base.

It turned out that by chance, Zheng Tao and the others wanted to worship themselves as teachers, but Xu Yun could only take a step back, which forced the interest group to come out in advance.

But whether it is active or passive, one thing remains the same:

That is, Xu Yun is going to use the abilities of these youth version of the boss to do something.

At the same time, he also wanted to see if he could export some knowledge of future generations, and try to make it easier for the Chinese physics community in this timeline.

After all, according to the normal development.

The Chinese physics community will face pressure from Europe and the United States for the next 60 years, and it was not relieved until the advent of lone point particles.

Whether it is selfishness or justice, there is a prerequisite task that must be resolved:

That is to obtain the approval of this small group.

Of course.

It’s still the same sentence repeated countless times.

What Xu Yun needed was not to be accepted as a younger brother, and he was not qualified to let these men of great merit call him his elder brother.

The recognition he needs is more of an equal acceptance, similar to that of friends of the same age.

According to the current situation

This pre-task should be regarded as a preliminary solution.

At least

These bigwigs will not publicly question their status as 'consultants'.

Then Xu Yun returned to the original position with the help of Qiao Caihong.

Zheng Tao stood up while the iron was hot, and asked everyone:

"Comrades, do you have any other opinions on Comrade Han Li's role as a study consultant?"

“.”

Everyone at the scene was silent for a moment, and shook their heads one after another.

joke.

Everyone came to the interest group to learn knowledge, and now there is an obviously awesome boss in the group, who would be dissatisfied with such a thing?

To know.

Many of them were kings of papers when they were in school, but after arriving at the base, due to age and ability problems, basically they have not formally joined the theoretical project teams involved in their majors.

For example, Zheng Tao and Zhou Shaoping decided to appoint them.

These two brothers are usually responsible for all kinds of physical work, such as the casting of Xu Yun's wheelchair, and various tasks of the construction sideline team.

So now there is such an interest group that can exchange knowledge, and there are consultants like Xu Yun in the group

It is not an exaggeration to say.

Some members already wished they could lie on Xu Yun's body and **** their brains. Ahem, to gain knowledge.

Then everyone chatted briefly.

Some are small phenomena encountered during work like balloons, such as the water hammer phenomenon where the water pipe keeps sizzling.

Some exchanged the usual reading materials.

For example, "The Hunter's Girl", "Red Flag Canal", "Fire King Kong", "Flower Shadows Beyond the Curtain" and so on.

During the period, Xu Yun would occasionally interject a few words, but most of the time he chose to listen in.

After all, this kind of discussion is like the LOL of the later period.

Carrying alone is actually very boring. At most, after 1V5, someone sends you a few question marks to express your shock, and then there is a dull emptiness.

But Happy Wuhei is different. That is the real happiness, which is much more interesting than frying fish alone or even going on a blind date.

that's all.

Two hours later.

The first group event of the 'Never Update' interest group has come to a successful conclusion.

The group members parted ways, and many of them had work to do in the afternoon.

Qiao Caihong pushed Xu Yun's wheelchair, preparing to go back to the hospital to continue today's treatment.

As a result, the two of them didn't go far.

A familiar greeting came from behind Xu Yun:

"Comrade Han Li, stop!"

Qiao Caihong hurriedly stopped.

Xu Yun turned his head and looked at the speaker.

I saw this moment.