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

"Also, save face! Don't stand up and refute my problem-solving ideas in class, do you hear me?"

Qin Fangming was scared!

As soon as this word comes out.

The jaws of the other students almost fell to the ground.

Although I heard that Xu Heng taught the class in the original class, and even let the whole class get the first place in the exam, but it is not possible to finish all the courses!

It's too fierce!

One month!

How on earth is this done?

What's even more unbelievable is that Qin Fangming still said that.

I always feel that Qin Fangming is afraid!

A physics teacher was afraid of his classmates in his original class!

And he was still afraid that they would stand up and refute his problem-solving ideas!

The three views are subverted!

The other students were taken aback.

Tang Yongxue and others suddenly felt superior!

That kind of carefree feeling rises from the soles of the feet!

Cool!

It turns out that this is a great feeling!

They looked at Xu Heng in unison, their eyes full of gratitude.

"Giggle..."

"Teacher, let's give a lecture! We promise to hold back!"

Qin Fangming's face turned dark, "What do you mean by guaranteeing to hold back? In this way, you can learn from Xu Heng and sleep again!"

It's all over!

Qin Fangming was really scared!

Although in the eyes of all the students, this physics teacher has already lost face.

But if Qin Fangming didn't do this, it would be even more embarrassing if he was refuted by these guys during class!

After this class, Qin Fangming felt like he was walking on thin ice, and he felt anxious.

For some topics, he has to follow the teaching materials. He also knows Xu Heng's thinking, but he can't talk about it!

It's done in a few minutes, how will he arrange the next class?

Sometimes, in some cases, the teacher has to speak according to the requirements, and the audience should be the vast majority, not just take care of a few people...  …

A teacher is not responsible for one person, or several people, but for one class, or several classes.

"Ring Ling Ling..."

When the get out of class bell rang, Qin Fangming breathed a sigh of relief.

Looking at Xu Heng, he slowly straightened up and stretched himself.

Qin Fangming had black lines on his face.

"%%￥##￥%..."

"Xu Heng, come here."

The relatives took Xu Heng for a walk.

"Aren't you planning on escorting?"

Xu Heng, "Yeah."

Qin Fangming persuaded, "Actually, recommending is good for you. You do well in the exam once or twice, but what if one of them fails?"

"But the recommendation is different, and there is no need to take the exam."

"Although you are sure of your success, but after the recommendation, you are sure of it!"

Xu Heng smiled, "Teacher, are you mainly trying to persuade me?"

Qin Fangming's smiling face became embarrassed.

"Ahem! Actually, I still have a few topics I want to discuss with you!"

Xu Heng, "To your office?"

Qin Fangming, "Yes, I will give you the problem, and you can take it back to read. I want to see what your thinking is about solving the problem!"

"I know you have a mobile phone. I'll add you as a friend. You can come up with an idea to solve the problem. When you have the answer, just tell me!"

Xu Heng, "A lot of questions?"

Qin Fangming, "Not much!"

Not much, that would take so much time.

When he came to the office, Xu Heng picked up the title and looked at it.

As shown in the figure, a balloon is at rest in the wind, and the force of the wind on the balloon is horizontal to the right.The angle between the thin rope and the vertical direction is a, and the tension of the rope is T, then the force F of the wind on the balloon is ()

AT/sina

BT/cosa

C. Tsina

D. Tcosa

Qin Fangming, "Go back and think about it first..."

"Think about it" Before he could finish the four words, Xu Heng interrupted him.

"Suppose a=0, then F=0, and there is no wind, put a=0 into it, and the answer comes out C!"

simple!

rough!

Before Qin Fangming finished speaking, his answers and ideas for solving the problems came out directly.

Qin Fangming was stunned, at a loss for what to do.

Xu Heng didn't give him a chance to respond, and read the second question again.

As shown in the figure, two objects with masses m1 and m2 are connected by a light spring, and under the action of a force F, they move together in a straight line at a uniform speed in the horizontal direction (m1 is on the ground, m2 is in the air), and the force F is proportional to the horizontal direction. theta.Then the correct support force N and friction force f of m1 is ()

AN=m1g=m2g-Fsinθ

BN=m1g+m2g-Fcosθ

Cf=Fcosθ

Df=Fsinθ

Xu Heng, "Assuming that θ is 90, the value of 0.3 slides upwards, so N=m1g+m2g-F, so the friction force f=0, the answer is AC!"

too fast!

Qin Fangming was still in the shock of the first question, and Xu Heng finished the second question.

"These two questions have the same purpose, limit thinking, combine the questions, take the maximum value, minimum value, or the most appropriate value."

Look at the third question.

Hot isostatic pressing equipment is widely used in material processing.

When the equipment is working, the inert gas is first pressed into a pre-vacuumized furnace cavity with a compressor at room temperature, and then the temperature of the furnace cavity is raised, and the high temperature and high pressure environment is used to process the materials placed in the furnace cavity to improve its performance.

The remaining volume V=0.13m3 in the furnace cavity of a hot isostatic pressing equipment after solid materials are put in once. After the furnace cavity is evacuated, 10 bottles of argon are injected into the furnace cavity with a compressor at room temperature.

已知每瓶氩气的容积V1= ×10（－2次方）m3，使用前瓶中气体压强P1=1.5×10(7次方)Pa，使用后瓶中剩余气体压强P2=2.0×10（6次方）Pa；室温温度T=27℃。氩气可视为理想气体。

(1) Find the pressure of the gas at room temperature in the furnace cavity after being pressed into the argon;

(2) Heat the furnace cavity filled with argon to 1227°C, find the pressure of the gas in the furnace cavity at this time.

Xu Hengran is like an emotionless answering machine.

The corners of Qin Fangming's eyes twitched fiercely, and he stared at Xu Heng.

He couldn't believe that Xu Heng was able to answer the question in just a 10-minute class break and wasted 2 minutes on the road!

Especially this last question...

PS: Thank you [Snow in June] [tail number 8818] for your support!

Ask for all support! .

Chapter 123

Qin Fangming was suspicious.

Xu Heng spoke again, "Look at the argon first..."

"Wait! Wait!"

Qin Fangming's hairs were about to stand on his head.

"Xu Heng! Have you finished reading the questions? You just say it! This is a calculation question, which is different from the previous multiple-choice questions. You..."

Xu Heng looked at Qin Fangming with such indifferent eyes.

Qin Fangming stopped suddenly and became speechless.

"You, you say it...you say it! Listen to you, you say it!"

Xu Heng, "A part of the argon gas is removed, and the remaining part is P2. The remaining volume is V1, and the removed part is V2. This process is isothermal. Let me list a split-state formula."

“P1V1=P2V1+P2V2，可以把这个V2解出来。”

"And which part hits the oven cavity?"

"Naturally, it's the part of V2!"

Xu Heng spoke as if he was a teacher and Qin Fangming was a student.

The identities of the two have been switched!

And Qin Fangming didn't realize it, and followed Xu Heng's train of thought, looking at the question.

Xu Heng continued, "The final pressure is P3, V."

“再列一个分态公式，因为是打了10次，所以得：10*P2V2=P3V，所以P3就可以求出来了。”

"The first question is easy to handle."

easy?

hiss……

According to Xu Heng's way of thinking, it is indeed very easy!

Xu Heng, "Let's look at the second question, it's actually easier!"

"It is essentially an isovolumetric change, because the volume of the furnace chamber remains unchanged, and the temperature changes from T0 to T1, so this equation is obtained."

Xu Heng wrote down on the paper:

P3/T0=P4/T1

"In this way, P4 can be obtained."

After speaking, Xu Heng stopped.

Before Qin Fangming's eyes, the three questions swept across like a storm.

He was stunned.