Xueba, I beg you to go and escort him quickly!

"Have you noticed now that although these two forces are opposite..."

was talking.

Qin Fangming walked up to Xu Heng, bowed slightly, and presented the chalk in front of Xu Heng with both hands, "Student Xu Heng! Come on!"

Xu Heng, "???"

"Teacher, what do you mean?"

Qin Fangming, "Let's talk about it! Mobilize everyone's enthusiasm!"

Xu Heng waved his hand and immediately refused, "I'm not a teacher."

Qin Fangming, "*%￥##￥..."

Xu Heng rolled his eyes, "Teacher, you are not so stingy, are you? Don't worry, I will tell Yue Pingting alone..."

Before he finished speaking, Xu Heng raised his head, only then did he realize that the eyes of all the students around him were focused on him.

Xu Heng had black lines on his face, "*%￥#@￥......"

The students sitting in the back two rows are all top students in the class.

At this moment, they all listened carefully to what Xu Heng said, with great interest.

Nima...

What are you looking at me for?

My voice is not loud!

Xu Heng looked at Yue Pingting suspiciously, "I have a loud voice?"

Yue Pingting, "It's not big, but everyone pays close attention to your voice..."

Xu Heng, "..."

Xu Heng looked at Qin Fangming, "Teacher Qin, I won't talk anymore, is that okay?"

Can--

Qin Fangming had already stuffed the chalk into Xu Heng's hand.

Xu Heng became anxious, "Teacher! Teacher...Teacher..."

Qin Fangming couldn't hold back anymore, his expression began to twist, "Student Xu Heng! There are three urgencies! Help! I'll go first!"

Qin Fangming didn't want to say it clearly, after all, this was a very embarrassing time.

But things have come to this point, and it is almost too late.

So that's all he can do!

Putting down the chalk, whoosh, he ran out of the classroom.

Xu Heng was ordered in the face of danger!

Everyone in the class looked at Xu Heng.

"Forehead……"

Xu Heng stood up slowly, "Hey... let's do it!"

He walked up to the podium slowly and looked at the four students.

"Don't let the four of you go, everyone, just go and try it! It's okay! If you don't believe it, you can try it."

After what Xu Heng said, many people got up and wanted to try it.

Especially boys.

After they tried it, they really couldn't get up!

They all stared wide-eyed, dumbfounded.

"???"

"I'm going! What's going on here? What's the situation...?"

"It must be related to the knowledge of physics!"

Most of the students in school are talking on paper!

In real life, you cannot apply what you have learned.

Xu Heng didn't expect them to understand either.

After all, after the boys failed, they were still very pleasantly surprised, "It's amazing!"

"What's the situation? Magic?"

"???"

"This trick, in ancient times, can be regarded as a magic to control people!"

Xu Heng, "%￥@￥￥%..."

"Okay, if everyone has tried it, look at the blackboard!"

Xu Heng repeated what he and Yue Pingting had said, and then continued.

He drew a sketch on the blackboard.

"Although these two forces are opposite, they are not collinear!"

"Such two forces cannot maintain human balance."

A classmate said directly, "Why can people stand against the wall at this time, can they withstand it?"

Without a teacher, because it was Xu Heng who gave the lecture, they were less worried.

If there is a problem, it is raised directly.

Xu Heng, "Because the wall will give people a support force, and the ground will also give people a friction force.

"Under the action of these four forces, people are in a state of balance."

"it is good!"

"Now this person is going to start coming off the wall!"

"Get off the wall and lift the chair, why is it so difficult!"

"Obviously, after breaking away from the wall, the person's gravity is still there, and so is the support under his feet."

"But because it is separated from the wall, the wall does not give him support, and the friction force is naturally unnecessary."

"The gravity and the supporting force are opposite, but not collinear, so under the action of such a force couple, the person will fall to one side."

"Here, let me tell you about force puppets!"

When the word "force couple" was mentioned, the students' eyes lit up even more.

Xu Heng not only gave a lecture, but also brought them something that was not in the textbook.

This stimulates their psychological sense of accomplishment.

Xu Heng, "A force couple is a pair of equal, opposite and non-collinear forces acting on the same object."

"The force couple produces a rotational effect on the object, and its measure is expressed by the couple moment, that is, the product of the magnitude of any one of the forces and the vertical distance between the lines of action of the two forces."

"A force couple is the action of two forces that are equal in magnitude, opposite in direction, and parallel to each other."

"It produces a purely rotational effect on objects..."

"..."

Xu Heng explained it well.

All the students understood it.

Just then.

The principal, Xue Laiyun, and Kevin passed by Class 25 of the second year of high school chatting.

Coincidentally, Kevin also talked about Xu Heng.

"Xu Heng is really surprising!"

"When I was teaching at Jingyun University, I had to attend the Calligraphy Association. I was never as busy as him!"

"He is much busier as a student than the teacher!"

Principal, "Yes! That's why Xu Heng should take a good rest during class."

Xue Laiyun also nodded, "Yes!"

The three of them talked and looked at Class 25 in unison.

"It turned out to be a physics class..."

Ah!

Physics class!

and many more! ! !

Hemp egg!

Yes, yes yes, it was Xu Heng who was giving the lecture!

Kevin was the first to be stunned, and opened his mouth wide, "This, this, this, the principal and Mr. Xue, you haven't told me that Xu Heng is still in charge of substitute class, right?"

Principal, "%￥#￥%!"

Xue Laiyun, "???"

This……

Looking at the classroom, Xu Heng spoke vividly, and the students listened carefully.

Kevin, the principal, and Xue Laiyun looked at each other.

Kevin, "Hiss...it turns out that student Xu Heng holds several jobs! Can he, he, he be busy? I'm really worried about him!"

Principal, "%￥#￥￥%..."

Xue Laiyun, "%￥@￥..."

Kevin, "Is there such a shortage of teachers in our school? I can introduce some friends! Principal, do you think it's okay?"

Three people stood at the window.

Listening to Xu Heng's lecture.

"At this time, you will find that you can't do without!"

"But why can girls leave? Because most girls have smaller feet than boys."

"If the feet are smaller, the posture of her legs is likely to be like this..."

"..."

"In this case, her support is on the feet, so her gravity..."

Xu Heng wrote while talking, very comfortable.

Xue Laiyun muttered, "Mr. Kaiwen, if I say that this is the first time Xu Heng is teaching our class, would you believe me?"

Kevin, "!!!"

"Teacher Xue, do you think I'm a fool? He speaks so well! The typhoon is very stable!"

Xue Laiyun, "%￥##%..."

Kevin frowned, and looked at the principal seriously, "Mr. Principal, is this really okay?"

"What did you guys do to classmate Xu Heng? He's just a student!"

Kevin said excitedly, Qin Fangming finally came back at this time.

He clutched his stomach, and heaved a long sigh of relief, "Huh... I finally feel comfortable, I almost missed it..."

Just turn the corner.

What the hell!

Qin Fangming found the principal, Xue Laiyun and Kevin by the window of class 25.