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

Look at the question:

As an instrument for measuring the acceleration of moving objects, "accelerometer" has been widely used in the guidance systems of aircraft, submarines, spacecraft and other devices.

As shown in the figure is the schematic diagram of the "strain accelerometer". Brackets A and B are fixed on the system to be tested. The slider is passed through the horizontal smooth rod between A and B and fixed on the bracket A with a light spring. As the system moves horizontally, the slider moves relative to the bracket, and the sliding arm at the lower end of the slider can slide freely on the sliding rheostat accordingly, and is converted into electrical signals by the circuit and output from the 1 and 2 terminals.

It is known that the mass of the slider is m, the spring stiffness coefficient is k, the electromotive force of the power supply is E, and the internal resistance is r. The resistance of the sliding rheostat changes uniformly with the length, its total resistance R=4r, and the effective total length L. When the system is at rest, the voltage U1=E output by the two terminals 2 and 0, the direction from A to B is taken as the positive direction.

(1) Determine the measurement range of the "accelerometer".

(2) Connect a voltmeter with a large internal resistance between the two terminals 1 and 2, whose reading is U, and derive the calculation formula for acceleration.

(3) Try to connect an ammeter with no internal resistance between the 1 and 2 terminals, the reading is I, and derive the calculation formula of acceleration.

"Shhhhh..."

The girl next to her didn't look up, she was still looking at the question with frowning.

Xu Heng picked up his pen.

Start the writing process.

But first he paused, how to write?

Write more specifically?

But how specific does it have to be so that she can understand it?

The topic is hard for Xu Heng, but how to write the process is hard for Xu Heng.

He glanced at the way the other party played on the paper.

Ok!

Just give it a try as you do.

Xu Heng slowly wrote:

"When the system under test is stationary, the output voltage U1=[ε/(R+r)]*R2"

"It can be deduced from the known condition U0=ε: R12=2r, at this time the slide P is located at the midpoint of the rheostat..."

"..."

"So the measuring range of the accelerometer is [-(kL)/2m)*(kL)/2m)]."

Xu Heng already got the answer to the first question, glanced at the other party, she was still answering the first question.

Xu Heng went on to the second question, "When the two terminals 1 and 2 are connected to a voltmeter, if P is shifted from the midpoint to the left by x, then the part connected in parallel with the voltmeter..."

The third question, "...by Ohm's law in a closed circuit...according to Newton's second law..."

"Simultaneously combine the above three formulas to get: a=[kL(ε-3Ir)]/(4Imr)."

Get it!

After finishing writing easily, Xu Heng handed over the paper.

At this time, Zhou Moyan also came back.

The girl's first question...hasn't come out yet.Four.

Chapter 192

She was deep in thought.

He didn't pay much attention to the answering process that Xu Heng handed over.

Because in her subconscious mind, even if the other party is the senior, even if the other party is the senior of Yao Ban, it is impossible for him to answer so fast!

It's not possible at all!

So in her consciousness, what Xu Heng handed over was not an answer at all.

So she didn't even look at it.

At this time, Xu Heng said softly, "I'll give you the answer."

"Don't think about it, because your thinking is wrong, so you can't solve it..."

clap la la...

The voice is gentle, like the spring breeze in March, bathing people's hearts.

The girl suddenly raised her head and turned to look at Xu Heng.

brush!

She blushed!

"You, you, you are not Senior Zhou..."

"Sorry! Sorry! I thought you were Senior Zhou, so, so..."

Xu Heng, "Let's take a look at your question!"

Girls are embarrassing!

She turned her head and looked around, Zhou Moyan was beside her.

"This this……?"

Zhou Moyan nodded at her, "This one is amazing! Trust him."

The girl curled her lips, "How is that possible! He solved the answer in just a few minutes! Senior Zhou, is he better than you...?"

Zhou Moyan nodded earnestly without flinching.

"Indeed, he is stronger than me, and much more powerful."

The girl thought Zhou Moyan was flattering Xu Heng, so she was a little skeptical.

She lowered her head and carefully watched the problem-solving process, and she gradually entered the state.

So much so that the person sitting next to her changed back to Zhou Moyan, but she still didn't notice.

After reading all of them, she turned her head to look at this side.

"Cock!"

She was startled, "Senior Zhou, why did you switch back to you again? Where is that senior?"

Zhou Moyan frowned, "Which senior? Which senior?"

She was excited, "That's the one! The one who was here just now!"

Zhou Moyan was relieved, "He's not a senior!"

The girl lost her mind for a moment, "You mean he is in the same class as me? Is he from the Yao class? God!"

Zhou Moyan hurriedly explained, "No! He is not from Yao Ban, nor from Tsinghua University, and he is not a student of our school!"

The girl opened her mouth wide, "???"

Zhou Moyan, "He's not as old as you! He hasn't taken the college entrance examination yet! He's a sophomore in high school..."

girl,"!!!"

In an instant, she handed Xu Heng's problem-solving ideas to Zhou Moyan, "Senior Zhou, help me to see, this...isn't it?"

Zhou Moyan waved his hand, "Don't look! What I said before was not a compliment, nor a joke!"

"He does have such strength! Don't worry about the questions he does! Sometimes, I also ask him for advice!"

The seniors of the Tsinghua Yao class actually need to ask others for advice?

In this girl's cognition, Yao Ban is the N0.1 existence in terms of learning.

But now, this senior from Class Yao slapped her in the face abruptly!

What's more terrible is that this Yao class senior didn't ask the professor, but a classmate who didn't even take the college entrance examination.

"???"

"This this……???"

Zhou Moyan smiled, "I know you find it incredible, but that's the truth!"

Zhou Moyan looked at the problem-solving ideas that Xu Heng wrote to her.

"He has treated you very well. He returned these words to you and explained the process clearly for you. If it were me, a formula and a theorem."

Girl, "Ah...?"

Zhou Moyan, "So, you really need to thank him more."

"But you don't have a chance now, let's do it in the future! Anyway, he will stay in Tsinghua University for a while."

The girl frowned, "Is he here to participate in the Olympiad training camp?"

Zhou Moyan nodded.

The girl was a little confused, "Wait a minute, I didn't realize it, participating in Mathematical Olympiad...Physics is so good... Hey! Are... are all high school students this good?"

"My God!"

She covered her mouth in horror.

Zhou Moyan gave her a blank look, "You think too much! Xu Heng, this is the only one."

Xu Heng? ! ! !

Rumbling--

This name is like thunder!

The girl almost screamed in the library, but she still tried her best to cover her mouth and minimize the amount of noise she made!

"!!!"

Wait for her to calm down a little.

Only then did she dare to let go, "Senior! Is he Xu Heng who is also very good at Chinese?"

Before, she paid attention to Xu Heng because of Xu Heng's composition in classical Chinese.

"My God! My God! My God! It turns out that she is not only good at Chinese, but also good at mathematics and physics..."

Zhou Moyan, "Did you connect to the Internet at home at first, but then disconnected?"

girl,"???"

"Senior, what do you mean?"

Zhou Moyan, "You paid attention to Xu Heng because of the composition, and you didn't pay attention after that?"

The girl was taken aback, "I've been paying attention to writing! Because I really like writing. Although I chose science in college, it doesn't affect my love of writing!"

Zhou Moyan shook his head helplessly, and said, "Then go and check Xu Heng online!"

"Learn more about it."

The girl curled her lips, "I'd better study first! I'll look it up when I'm free!"

Zhou Moyan packed up the books on the table, "Let's go, goodbye."

Go to the other side of the bookshelf, help Fu Xidong pick a few books, and the two leave together.

Fu Xidong, "Where's Xu Heng?"

Zhou Moyan, "Let's go first."

Fu Xidong showed disappointment, "Ah! Just left like this? Hey..."

Zhou Moyan, "Recently, he has been in Tsinghua University, and I often see him by chance."

Fu Xidong nodded, "That's right!"

……

Xu Heng who left left directly. When he reached the school gate, he got into Han Honghu's car directly.

"Mr. Xu, the pass is ready for us! It's really efficient!"

"I will pick you up and send you off in the future, so you don't need to run any longer!"