I have few friends, but many childhood sweethearts.

Chapter 244. We need to talk about this Lin Wanning.
"Brother Qingfan, I have a question I don't understand." After the physics class ended, Lin Wanning asked about the part he didn't understand, as usual.

"Go on," Xu Qingfan said, turning his gaze away from the scenery. Despite having been lost in thought for the entire class, he could still easily answer the simple junior high physics questions.

"The teacher just said that since the buoyancy coefficient (F_buoyancy) equals the water level (G_water), the water level won't change after the ice melts. But why does the TV always say that global warming is causing glaciers to melt and sea levels to rise? Shouldn't the water level remain the same?" The girl asked, resting her chin on her hand, voicing a question that puzzled her.

The others, upon first hearing this, seemed to find it quite reasonable, and all turned their gazes to Xu Qingfan, awaiting the answer to the question.

“What’s so confusing about that?” He reached out and flicked Lin Wanning’s ahoge (cowlick), explaining, “Because not all glaciers float on the water’s surface. There are also many snow-capped mountains and the like. The water flowing down after the snow melts causes sea levels to rise.”

"Oh, right!" the girl exclaimed, suddenly understanding.

"If there's an iron ball inside the ice, the water level will drop after it melts. Do you know why?" Xu Qingfan suddenly remembered a question he had done before and asked the group.

"The gravity is greater than the buoyancy later on," Xia Xiaoxiao replied without much thought.

"The buoyancy has decreased," Wu Lingyu said less than three seconds later.

“Yes.” After being enlightened by the two, Zhang Yiyi quickly figured out the reason for the descent.

"Huh?" Only Xiao Ruanwen and Lin Wanning were a few beats slower to react, their minds still not quite processing what was happening.

"Why is the buoyancy smaller? When floating on the water, aren't the two forces in equilibrium, with gravity equal to buoyancy?" Xiao Ruanwen asked.

"It's an iron ball, the iron ball sank to the bottom," Xia Xiaoxiao explained.

"I don't understand." Lin Wanning shook his head vigorously, just about to ask Xu Qingfan for an answer.

"I'm going to the restroom. You can let Xiaoxiao teach you." He patted the girl's shoulder and got up from his seat.

"Hehe, okay, I'll definitely figure it out before Brother Qingfan comes back!" Lin Wanning promised.

Xu Qingfan simply smiled and did not answer.

The water dispenser in their school building was built next to the toilet. Xu Qingfan always felt that the water in it was the same as the water used to flush the toilet. He didn't know if it was his subconscious, but it always smelled strange. So he didn't bring his water bottle to get water when he went to the toilet.

Furthermore, the toilets inside are also full of flaws. Forget about squat toilets with doors and Western-style toilets like those in their experimental primary school. There is only a small water channel about seven or eight meters long and a few squat toilets separated by a half-meter-high wall.

Therefore, anyone who dares to poop a big poop during break time will be laughed at for a week, and in more serious cases, they will be bullied by their classmates.

Even someone as strong as Xu Qingfan wouldn't dare to squat in the toilet during breaks. Passing students would be staring at you, which would be too risky, not to mention who knows if there were any Nantong fencers among them.

After one of the people in the canal left, Xu Qingfan stood up and took out his big gun to flexibly assemble a group of five or six people.

The sound of the water tap immediately attracted the attention of the other trickling streams. He didn't want to be so conspicuous, but his strength wouldn't allow it.

[Damn it, why don't they compare themselves to Black people!]
Worried about making his classmates feel inferior, Xu Qingfan shook himself off after finishing his fight, quickly put on his pants, washed his hands, and left. As he walked, he habitually pinched his chin, only to realize that his longest whisker had grown to five or six centimeters long.

"I need to buy a razor when I get back," Xu Qingfan muttered to himself.

It has to be said that time really flies. When he first stepped into this campus, he was only about 1.5 meters tall, but now he is already 1.73 meters tall.

Nearly four months have passed since Lin Wanning had her first period. The girl, who used to look like a primary school student, is now almost 1.6 meters tall, and her small breasts are no longer small A cups.

Xu Qingfan noticed this when she was hanging up the laundry. After returning home for a holiday, when she went back to school, the girl's usual tank top had been replaced with a bra that only older girls would wear.

She still has the same personality as an elementary school student, always wanting to cuddle with her brother Qingfan.

[I really have to talk to this silly girl.] Xu Qingfan thought to himself about when to have another talk with the girl. This kind of behavior, like crawling into bed, which clearly crosses the line between normal brother and sister, really shouldn't happen again.

He had mentioned it to Lin Wanning several times before, but the girl always laughed it off. This was partly because Lin Wanning hadn't developed yet, and partly because the girl was genuinely adorable.

The charm of a young Wan Ning is irresistible to anyone, which is why things always end up unresolved.

[This time, we absolutely cannot let it end like this again!]
After returning to his seat in the classroom, Lin Wanning pulled out three tissues to wipe his hands, and said eagerly, "Brother Qingfan, I understand now! After the iron ball sank to the bottom, its gravity became greater than its buoyancy, which is no longer the case when gravity equaled buoyancy. That's why the water level dropped!"

“Not bad, not bad. What if the iron ball is hollow, and the ice melts and it floats in the water, or floats on the surface of the water?” Xu Qingfan asked, drawing inferences from one instance to another, and then posed two more questions to test the teacher.

"Ugh~ there are ducks too?" The girl complained, but she still seriously picked up her pen and started writing formulas and force analysis diagrams on the draft paper.

[It would be embarrassing for Wan Ning to talk about that in front of everyone. Let's wait until we're alone to discuss it.]
After a while, the girl exclaimed in surprise, "Brother Qingfan, I understand! It's all the same, right?"

"Because gravity is always equal to buoyancy, the two forces are in equilibrium. If the iron ball just reaches the bottom of the water but does not exert pressure on the ground, it remains unchanged!" It seems that Lin Wanning has really mastered the chapter on buoyancy and can even apply it to other situations.

"Wan Ning is amazing." Xiao Ruanwen thought about it and agreed, giving her a thumbs up.

"That's right, keep it up, here's a little red flower for you." Xu Qingfan made a sticker-sticking motion, pretending to stick a little red flower on her forehead.

"Hee hee~"

Encouraged, the girl gained confidence and no longer found the difficult physics problems boring. Instead, she felt a sense of excitement from challenging herself.

The wind blew the curtains and brushed against my face, then blew over my head. The afterglow shone through the glass and fell on me. The sunset at school always seemed exceptionally beautiful.

The last self-study session came to an end in this atmosphere.

(End of this chapter)