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

The ancients have studied this kind of thing for more than 2000 years.

The teacher talked a lot and talked a lot.

Xu Heng also nodded.

but--

From his personal point of view, this question is still too simple.

"You guys think about it again! Change the type of question!"

"Otherwise, junior high school students can solve this kind of problem."

Everyone, "%￥#@#￥%￥#..."

Xu Heng passed by the biology group.

They're talking about kinesins.

It is a small video that went viral on the Internet before, saying that a kinesin, also known as the porter in the cell, is also called a molecular motor, which can walk leisurely with cargo hundreds of times heavier than itself.

These biology teachers have to come up with a question based on this thing.

Xu Heng directly exposed it, "Which video did you base your question on?"

Teachers, "Yes."

Xu Heng, "I'm sad...but there was an error in that video."

Everyone, "???"

Xu Heng, "Kinesins can walk 100 to 250 steps per second."

Point broken.

Xu Heng went to the next group.

Because time was limited, Xu Heng basically didn't have one more word of nonsense.

In the language group, Xu Heng saw a couplet:

But stand without confusion and know the destiny, sixties are seventy years old.

Xu Heng said bluntly, "Isn't this a curse? Isn't it 250 when added up?"

Everyone came to their senses, "!!!"

Xu Heng smiled and walked between the nine subjects.

At the same time, he also faced a variety of questions and gave answers easily.

"Student Xu Heng! Let's take a look at this question!"

Xu Heng came over after hearing the news.

topic:

As shown in the figure, in the region of 0≤x≤h, -∞y+∞, there is a uniform magnetic field with a direction perpendicular to the paper surface, and the magnetic induction B can be adjusted in magnitude, but its direction remains unchanged.

A particle with mass m and electric charge q (q0) enters the magnetic field from the left side of the magnetic field region along the x-axis with velocity v0, regardless of gravity.

(1) If the particle leaves the magnetic field through the positive semi-axis of the y-axis after being deflected by the magnetic field, analyze the direction of the magnetic field, and find the minimum value Bm of the magnetic induction in this case;

(2) If the magnitude of the magnetic induction is Bm/2, the particle will leave the magnetic field through a point on the boundary indicated by the dotted line.Find the angle between the moving direction of the particle at the point and the positive direction of the x-axis and the distance from the point to the x-axis.

After Xu Heng finished reading, he fell silent.

This question examines some knowledge points such as magnetic field and Lorentz force.

The teachers in the physics group stared at Xu Heng, "Student Xu Heng, what's your opinion?"

Xu Heng, "This question is not bad, a very good question, but, there is no need to make it a big question, right?"

"At most it's a fill-in-the-blank question, or a multiple-choice question, or something!"

"Wouldn't it be a waste of time to use this question on a big question?"

Everyone, "..."

Xu Heng, "No! No! Are there any other questions? Teachers!"

One suddenly said, "Yes, yes, yes!"

The question was directly in front of Xu Heng.

As shown in the figure, the mass of a vertical tube is M, the height of the lower end from the horizontal ground is H, and a small ball of mass m is plugged at the top.

The circular tube falls freely from rest, and has multiple elastic collisions with the ground, and the time of each collision is extremely short; during the movement, the tube always remains vertical.

It is known that M=4m, the sliding friction force between the ball and the tube is 4mg, and g is the magnitude of the acceleration of gravity, ignoring the air resistance.

(1) Find the respective accelerations of the tube and the ball at the moment after the tube collides with the ground for the first time;

(2) After the tube bounces off the ground for the first time, the ball does not slip out of the tube during the rising process, find the maximum height of the tube rising;

(3) During the rising process of the second bounce of the tube, the ball still does not slip out of the tube. Find the conditions that the length of the round tube should satisfy.

For this question, Xu Heng nodded.

This question has some advantages, and the question is quite novel.

Although the things asked in the topic are still old-fashioned, there is no problem with the idea of ​​the topic.

but

Xu Heng struggled again and again, but still asked, "Isn't it good to do a fill-in-the-blank or multiple-choice question? Why is it such a big question?"

"So, everyone, you still don't quite understand what I mean!"

"Teachers, why can't you be cruel?"

"In this way, I will propose a question, and you should follow my standard. Don't wait for the question to come out. It is difficult to fill in the blanks, but the big question turns out to be surprisingly simple."

Teachers, you look at me, and I look at you.

They all expressed doubts.

Every question here was solved after they discussed it together.

Although it didn't take a long time, it was only after a dozen or even dozens of teachers helped each other.

But Xu Heng asked them to turn these questions into fill-in-the-blank or multiple-choice questions.

They were a little surprised.

The topic is like this, why do you still think it is simple?

This is much more difficult than the questions we asked before!

Under the watchful eyes of everyone, Xu Heng wrote directly on the paper:

(1) Experiment with a simple pendulum with a pendulum length of 80.0cm, and the maximum angle of swing is required to be less than 5, then the distance to pull the pendulum ball away from the equilibrium position at the beginning should not exceed _______cm (reserve 1 decimal place). (Hint: When the simple pendulum is pulled apart by a small angle, the distance to be obtained is approximately equal to the distance traveled by the pendulum along the arc.)

A student wants to design a new pendulum, and requires that the time for the new pendulum to swing for 10 cycles is equal to the time for the original pendulum to swing for 11 cycles.The pendulum length of the new pendulum should be _______cm.

Xu Heng, "It would be nice to make such a fill-in-the-blank question!"

"Simple, direct! Right?"

The teachers took a closer look.

"I... this... Xu Heng, are you serious?"

"Yes! The question is simple and straightforward! But for candidates, the calculation amount of this question is even far greater than the calculation amount of our question!"

The expressions of the teachers changed immediately.

"This first question is okay! But the second question..."

Where did Xu Heng hear them say this?

Then write it down on paper.

The refractive index of the rectangular prism is n= , and its cross section is shown in the figure, where ∠C=90 and ∠A=30.A thin beam of light parallel to side BC in the cross-section enters from point D on side AB of the prism, and strikes side BC after being refracted.

① Will light be totally reflected on the side of BC? Explain the reason;

② Regardless of multiple reflections, find the sine of the angle between the light emitted from side AC and the initial incident light.

Xu Heng, "We're going to come up with big questions like this! Give candidates all kinds of possibilities to think about!"

Teachers, "!!!"

They have to obey!

Even if you don't accept it!

They can only hold back.

Xu Heng's strength lies here. The questions that people come up with are indeed simple and straightforward, which is much better than their tedious questions.

Sometimes, there are many words on the topic, but it does not mean how difficult it is!

"On the contrary, we have to use the fewest words to express the most accurate meaning. This is also a kind of respect for their candidates! We are not taking a Chinese test, so what kind of word games are we playing?"

After speaking, Xu Heng left.

Just arrived in the language group.

The topics they are preparing for their Chinese composition are some that Xu Heng and Yue Pingting have talked about.

Xu Heng pressed his eyebrows slightly, "Recent exams, many provinces, many provinces have used the subject matter."

"There are so many themes that candidates will find them annoying!"

"We want less! Less..."

Anyway, Xu Heng felt a headache when he saw the teachers in the language group talking about seven or eight lines of subject matter.

In the language group, these teachers' attitudes towards Xu Heng were obviously different.

They came here to discuss literature with Xu Heng!

No matter which aspect they start from, they are all cheerful, with smiles on their lips.

"Student Xu Heng, I have an idea for a car, how about you help me improve the materials?"

Composition materials are very important!

The idea, central idea, etc. of this composition, and many other things, all need to be shown through the subject matter.

Therefore, in terms of subject matter, we must grasp it well.

Sometimes, a good subject is even more difficult to write than a composition!

Because it is too difficult to grasp!

The teachers in the language group all looked at Xu Heng.

……

PS: The Chinese New Year is coming soon, so I am too busy!I also hope everyone Haihan!There will be no shortage of updates!Will definitely make it up!There will be updates later!

Kneel for all support!

Thanks to [●v●Xiao Chenxi~]【Xiyue 24】for your support!

I wish you a new year with abundant wealth and endless peach blossoms! .

Chapter 331

car?

In fact, many aspects can be seen from a single car, but it is not appropriate to write it in an article and let the car extend to other aspects.

After all, there are still certain differences between the composition and the influence of cars in real life, pronouns, etc.

Xu Heng thought and thought, and finally said, "Cars are inseparable from life. There are many types of cars and different shapes. Cars come and go, witnessing the development of the times, and carrying the true feelings of the times; cars coming and going, reflecting the The change of concept contains the philosophy of life.~”

Done.

The language group fell silent.

Teachers pondered over and over again, and your eyes lit up.