Scholar’s Starry Sea

Before braking, the center of mass of the truck and the heavy object are located at x₁ and x₂, respectively; after braking, the truck has moved the distance s₁ until it is completely stopped, and the two centers of mass are located at x₁'=x₁+ s₁ and x₂=x₂+s₁+L. So there is

”Δx=M+m of Mx'₁+mx'₂-M+m of Mx₁+mx₂=M+m of (M+m)s₁+ML =2u₁g divided by v²

This solution:

s₁=2u₁g divided by v²-M+m divided by mL

"Alas...GG, The impulse theorem is too tight, and there is not enough time to check it."

Wu Bin raised his head and sighed, rubbed the temple.

At this time, Gu Fan stretched his head and took a look at the densely packed 40 lines of calculations on Wu Bin's scratch paper on the desk, suck in a breath of cold air; "Have I really studied Physics?" "

"Well, you have learned it, but you haven't learned this yet." Wu Bin nodded.

"Then I really hope I never learn this, what is this? Rematch question?"

"No, it's a deploring memory." Wu Bin shook his head.

"Snake essence disease." Gu Fan moved towards him rolled the eyes.

When Wu Bin first returned to the classroom, the classmates originally planned to celebrate him with flowers, but when they saw Wu Bin's stunned look, they decided to look at him quietly.

After the fourth get out of class in the afternoon, Zhang Qiu ran to Wu Bin and asked: "I'll be curious about the questions for the rematch. If you are not in the mood to say, I will immediately shine."

p>

"Let's see for yourself." Wu Bin handed a few draft papers to Zhang Qiu.

"Thanks."

Zhang Qiu took the draft paper over and looked at it with a solemn expression.

"En...en, en~oh~whis..."

"You are singing." Gu Fan, who couldn't stand Zhang Qiu's weird accent, spit out.

And Zhang Qiu ignored Gu Fan, just gently put a few scraps of paper back on Wu Bin's desk and left a word before turning away.

"Just treat me...I haven't learned to compete."

This made Gu Fan amused, said with a smile: "It turns out that I am not the only one watching the co-author. I don't understand."

"Wu Bin, shall I go for dinner." At this moment, Xu Hao and Wang Qi came over and asked.

"You go first, I'll come over later."

Xu Hao and Wang Qi looked at each other, nodded, and stopped asking more.

"Let's go, let's hear that there is a lion head coming today." Gu Fan pushed the two of them and walked out of the classroom together.

Wu Bin, who was alone in the classroom, raised his head and closed his eyes, lost in thought.

After all, he is the first time he has participated in a competition of a competitive nature, and his desire to win is also unprecedentedly high.

Compete with others for ranking and break into the next round for more intense fighting after victory. What else can stimulate hormones more than this?

'Maybe next time I...'

"Hey, Wu Bin."

Wu Bin just started thinking, a voice suddenly interrupted her , Shivered him, after all, he thought there was no one in the class.

"It's scary, it's scary, classmate." Wu Bin opened his eyes and looked at Pei Jiamin in front of him and said.

Pei Jiamin listened to sorry laughed, "Sorry, I thought you heard my footsteps."

"Is something wrong?" Wu Bin asked, sitting upright. .

"Well, I just want to say something. I admire you for entering the semi-finals of the competition." Pei Jiamin said while looking at the door of the classroom from the corner of his eye, for fear that other students would like her Return to the classroom.

Even if some classmates came back, she just saw her and Wu Bin chatting far away, but she still felt that the heartbeat was very fast.

"Russian...actually, there is nothing to admire."

From Pei Jiamin's mouth that she admires herself, Wu Bin is still a bit dazed. Why did this woman suddenly change her sex? ?

“In fact, when I was in my first year of high school, I also thought about participating in Mathematics competitions, but the school didn’t pay much attention to competitions, and I couldn’t manage both competitions and normal studies.” Pei Jiamin wrote and secretly I glanced at the door of the classroom, found that there was still no one, and said, "So when my first test scores dropped, the teacher and my mother both came to persuade me to study hard and not to think about the competition."

"Well? Your grades have dropped? Have you had such a period?"

In Wu Bin's impression, this female Bookworm has always been among the best in the class.

"Yes, I fell from 8th grade to 17th grade during the mid-term exam in the first year of high school."

"Oh."

Click Wu Bin, who said the word "oh" with no expression on his face, only had'hehe at this moment' in his heart! '

Seeing Wu Bin nodded, Pei Jiamin went on and said: "At that time, I gave in. I gave up the competition and started to concentrate on studying, so when I heard you broke into the semi-finals of the Physics competition , I feel very admired, because you did what I didn’t do.

Before Wu Bin could respond, Pei Jiamin suddenly took out a can of ice coke and stuffed it into Wu Bin’s hands. , And said: "When you have troubles, you will feel more comfortable drinking something iced. "

"Russia...Thank you. "Wu Bin feels the cold nodded on the coke can.

"I believe that as long as you continue to work hard like this, you will be successful. "

After speaking, Pei Jiamin ran out of the classroom like flying away, his entire face flushed red.

"What's the situation..." Wu Bin scratched his hair with an inexplicable expression. .

'Maybe she...is a good person?'

'After all, she said she admired me, hahahahaha! It seems that she finally knows how good I am.'

' p>

After thinking about it, Wu Bin opened the tab of the Coke and took a few sips.

"Huh...it seems to be really comfortable, well, tomorrow Give her a bottle. "

Wu Bin, whose mood has improved, slowly swayed out of the classroom with Coke, moved towards the cafeteria.

……

3rd day, Wu Bin went to Bright Middle School to test the experimental questions.

One of the two experimental questions is the observation of the spectrum, and the other is the measurement of the magnetic field using the Hall effect, both of which are in the "Experiment Guide".

Wu Bin, as the experimental question "ghost", is naturally easy and smooth to do, so that the invigilators can't help but secretly nodded.

'40 points should be stable.'

After taking a deep breath, Wu Bin thought of it in the heart.

After returning to school, Wu Bin did not slack off the Physics competition because he might not be able to enter the provincial team. Instead, I became more obsessed with studying. Gu Fan, who was addicted to noon and wanted to ask him two questions, couldn’t speak very well.

Because Wu Bin’s whole body exudes that strangers should not enter and acquaintances should not come close. Aura.

Particulate kinematics, conservation of momentum, conservation of mechanical energy, conservation of angular momentum, rigid body mechanics, etc. Wu Bin once thought he had understood things, and now he has to study it again.

Just because he is not strong enough!