"On the horizontal ice surface with a horizontal thrust of size f=20n, the ice truck with a mass m=60kg starts to move from stationary momentum. ◎ The friction force the ice truck is 0.01 times its pressure on the ice surface. When the ice truck advances 30m and then removes the thrust f, the ice truck moves for a certain distance and stops. What is the speed and total distance of the ice truck when the thrust f is removed?"

The physics teacher pushed his glasses and saw that no one spoke, he could only look at the penultimate row by the window:

"Yang Chao, please answer!"

"According to the kinetic energy theorem, the change of the kinetic energy of an object is equal to the work done by combining external forces. According to the question, the mass of an object is known and will not change, so as long as the velocity of the first state and the final state can be calculated, the equation can be solved."

"The answer is correct, but why not use Newton's second law? Wouldn't that be easier to understand?"

The physics teacher looked at Yang Chao with a smile, not surprised that the student could answer this question.

"The entire object is divided into two states in the process of change. Using Newton's second law requires the force analysis of the two situations of the existence of thrust f and the absence of thrust f. However, using the kinetic energy theorem only requires the initial and final states, and no intermediate processes are required."

"The answer is correct, please sit down!"

As soon as Yang Chao sat down, a whisper sounded near him.

"So amazing!"

"Yes, Yang Chao is really amazing!"

"Why didn't I think it?"

Hearing the admiration around him, Yang Chao smiled faintly. Any student from China who has studied physics a little seriously will not be difficult to answer such questions. After all, China's basic education is far ahead of the world.

He turned his eyes outside the window, which was the school's bow department doing outdoor practice on the playground. Yang Chao glanced at him and found the familiar figure.

"Dingling!"

The bell rang for the end of get out of class. Yang Chao was immediately surrounded by a group of people.

"Student Yang Chao, please teach me how to do this question, right?"

"Student Yang Chao, let's go to the library to review this weekend?"

"Student Yang Chao, why don't you come to my house tonight?"

Just when Yang Chao was dizzy and uneasy because of the quarrels of these people, someone appeared and saved him in time: "Yang Chao, come to my office!"

Seeing that it was the teacher who spoke, the students stopped stopping and let him leave.

As soon as he entered the office, the teacher who brought Yang Chao to the office said seriously: "Yang Chao, I think we have to communicate some things."

"Tell me, what's the matter?"

Seeing that Yang Chao's expression was calm, the other party became anxious:

"Why are you still so calm? We have been here for three days, but so far there are only four of us here, and there is no news for the others! And we have never received any reminder from the system about the main task, and even the plot has not even begun. Don't you find it strange?"

"Calm down, Kong Zhang."

Yang Chao glanced at the reincarnationist whom he had known a long time ago and said slowly.

"How can you calm down when you tell me? It's fine if the main plot has not been unfolded, but so far, our number has been half reduced! The most important thing is that we have lost contact with Gong Weiyang! Don't forget why we came to this copy."

Looking at Kong Zhang's excited appearance, Yang Chao frowned slightly. After returning from the previous copy, his mentality changed fundamentally because he had experienced too many things, so he was a little disgusted with Kong Zhang's current performance.

No matter how disgusted he was, he was his ally after all. Yang Chao said patiently: "Even if you are anxious now, it will be useless. Gong Weiyang wants this dungeon. If he finds that he has lost contact with us, he will naturally find a way to come to us. As for the tasks you mentioned, I think the system will be released when those zombies start to appear."

"Of course I know this! Are we doing nothing now? I think you seem to enjoy being a top student!"

"So please tell me. What can we do now? Or do you think we can't deal with those zombies with our strength?"

Kong Zhang was immediately speechless.

"Enjoy the short peace before you, maybe the zombies will start invading tomorrow."

After leaving such a sentence, Yang Chao turned around and left the office.

In fact, Kong Zhang said one thing right, that is, Yang Chao really enjoyed such a peaceful life, especially after experiencing the previous copy of the mission.

There is still one class before school time, and after school, Yang Chao will go to the Guns and Door Department. Because in this copy, he is from the Guns and Door Department of Fujime Academy.

"Master! Is the event going on as usual today?"

A young girl suddenly ran over from the other side of the corridor and stopped in front of Yang Chao and asked.

"Well, go as usual!"

"Yeah! That's great! Do you know the Lord? Among the third-grade students, you are one of the few who are still participating in the event. Most of the third-grade leaders of the activity department have stopped the activity due to learning reasons!"

"Yeah?"

Yang Chao nodded, and he would not care about these things without commenting.

"By the way, the chief general of the Kendo tribe said she is coming to challenge you today."

"Is the Kendo Department?" Yang Chao said to himself.

evening.

Fujimi Academy Gundo Department Activity Room.

"Haikai, sit down a little longer and move the center of gravity down."

"Ono, you must be fast, your position must be accurate, and you must take action with force. Remember three words: fast, accurate, and ruthless!"

"Miyamoto, where are your eyes looking? If this were on the battlefield, you would have been killed by the enemy long ago!"

Yang Chao looked at the members of the Gun Lane Department who were undergoing training and corrected their mistakes in an orderly manner.

At the same time, people watching the training of the Gun Lane Department were also secretly talking.

"Senior Yang Chao is still as strict as ever!"

"Of course, since several of their Chinese exchange students came to our school last year, Senior Yang Chao has chosen the entire Gun Department alone! Do you know? The original leader Hikawa Takasaka was defeated without even catching Senior Yang Chao's move!"

"What, there is such a thing?"

"What do you think? Otherwise, how could the people from the Guns and Door Department convinced a Chinese exchange student to become the main general?"

"This is probably the legendary Chinese Kung Fu?"

"I think that's it."

At this moment, a mature female voice came from the door of the activity room:
Chapter completed!