From child prodigy to chief scientist

"Yang Dun, when you went to the toilet just now, did water splash onto your butt?"

Seeing that Xu Xiao had discovered the problem, Yang Dun scratched his head somewhat embarrassedly.

"Haha, Xu Xiao, you really know me. Let's not talk about that for now. This is actually a physics problem that's worth studying."

After thinking about it carefully, Xu Xiao also felt that this question was actually quite interesting.

If we consider it according to the model of ordinary elastic collision, the rebound speed should not exceed the initial velocity at the time of impact.

However, based on practical experience, such a model certainly has some problems.

「我们把这个问题转化为一个固体入水的问题。假设物体离水面h0=32厘米，按照自由落体去考虑，固体撞击水面的速度v0=√（2gh0），g取9.8……」

Youngton quickly transformed the problem into a theoretical model, which made the problem seem less interesting.

No sooner had Yang Dun finished speaking than Lü Yihang quickly gave his answer.

"I've calculated it, v0 is approximately 2.5 m/s."

Computational ability has always been one of Lü Yihang's strengths; even Xu Xiao and Yang Dun cannot compare to him in this aspect.

Xu Xiao had to admit defeat. He checked the calculation with a calculator and was surprised to find that Lü Yihang's result was accurate to two decimal places.

"Yes, an approximation is enough. This shouldn't be a model of elastic collision, because water is a fluid..."

As he spoke, Yang Dun pulled a book out of his cabinet.

University Fluid Mechanics

Everyone was already used to Yang Dun frequently bringing out university textbooks, and they all crowded around, looking in the direction Yang Dun was pointing.

"Look, isn't the problem we're studying very similar to Rayleigh cavity collapse models?"

This is a theoretical model describing the asymmetric annihilation process of bubbles in a liquid under high pressure. It is mainly used to analyze the pressure changes when a spherical cavity collapses in an infinite liquid.

Although the reality is not as ideal as the model requires, it can still be simplified.

"That's certainly a valid analysis. When a solid comes into contact with water, it doesn't bounce back directly; instead, it first displaces the water, creating a cavity that's almost bowl-shaped..."

"That's right. In that case, the surrounding water would need to fill the cavity, converge towards the center, and finally form a small jet. The mass of this jet would definitely be much smaller than the mass of the solid."

"Assuming the mass of the jet is one-quarter that of the solid, according to the law of conservation of energy and the kinetic energy theorem, the initial velocity of the jet is v' = 2v0, and the height of the splash is 4h0..."

"Damn, if that's the case, Yang Dun, the splash you just made was over a meter high! Even people who jump from a 1-meter platform don't make that much of a splash!"

"It shouldn't be that high. If we take energy loss into account, the splash height shouldn't reach 1 meter, but it should easily exceed the initial height."

After some calculations, the problem that Yang Dun had thought of had been basically solved.

However, Yang Dun's imagination did not end there, and he continued to think about ways to suppress the water splash.

"If the second solid can be released quickly after the first solid enters the water, it should be able to neutralize the first jet."

Ding Mosen understood what Yang Dun meant, and then shook his head and said:

"This method places too much strain on the sphincter muscles. It would be better to lay a few sheets of paper on the water beforehand, which would provide a better cushioning effect."

"That makes sense. It's like how divers hold their hands flat before entering the water to prevent creating a deep cavity," Lu Yihang agreed.

At this moment, Xu Xiao suddenly thought of something and said with a somewhat subtle expression:

"The crux of the problem is probably that you can't stretch your legs properly, right?"

Just now, when Yang Dun was in the toilet, Xu Xiao clearly heard a series of "plop" sounds, like stones being thrown into water.

Hearing Xu Xiao say this, Yang Dun suddenly realized what was going on.

"Now that you mention it... it does seem to make sense! If it were a long and thin shape, it definitely wouldn't have created a deep, bowl-shaped cavity."

"Or you can try to stay as close to the water surface as possible to minimize h0, and it's best to wait until it enters the water before snapping it off, then there will definitely be no splash."

After discussing this issue for a while, Xu Xiao felt it was about time to come to a close.

If the teachers found out they were discussing this in their dorm rooms at night, I wonder what their expressions would be like.

"Yang Dun, you've been auditing the high school physics competition training camp these past few days, haven't you? You weren't just studying these weird problems, were you?"

"No, the competition questions aren't that interesting. Actually, the high school physics competition is quite simple. I've already decided to sign up for this year's competition. Xu Xiao, why don't you sign up too?"

"Forget it, I'll just register for the college entrance exam. I lost almost 20 points on the physics section of the comprehensive science exam this month, and I definitely wouldn't know how to do the competition questions."

Xu Xiao has a fairly clear understanding of his own abilities. He is not a genius at all; he is just more experienced and mature than others.

High school competitions are a true contest between geniuses; without extraordinary talent, it's virtually impossible to stand out.

"Even if you're not good at physics, you can still sign up for a math competition. You've already scored over 140 in high school math, so you should definitely give it a try. It'll be another way to get into university."

After thinking about it, Xu Xiao felt that Yang Dun's words did make some sense.

Even if the chance is really slim, there's no harm in registering first.

Anyway, I'm still young, so I have plenty of opportunities to try and fail.

Hearing Xu Xiao and Yang Dun talking about the college entrance examination and high school competitions, Lü Yihang and Ding Mosen couldn't help but feel a little disappointed.

We're all roommates in the same dorm, so why is there such a big difference between us?

"Sigh, you guys are already researching high school competitions, while we've only just started getting into junior high competitions."

"Yeah, seeing how amazing you two are, we feel a lot of pressure."

Xu Xiao understood Lü Yihang and Ding Mosen's feelings, and immediately offered words of comfort:

"Don't think like that. You two are actually very good. Big Brother, your calculation ability is exceptional, and Little Fatty, your chemistry talent is also very strong."

"Big Guy" and "Little Fatty" were the nicknames of Lü Yihang and Ding Mosen in class, and Xu Xiao's evaluations of them were indeed very sincere.