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

Yue Pingting looked blank, "What are you doing? Xu Heng, what are you doing!"

slippers!

go to bed!

then……

Yue Pingting, "???"

She herself slipped into Xu Heng's arms by a strange coincidence.

Xu Heng slowly closed his eyes, looking a little satisfied, "It's still comfortable to sleep in your arms, and come back to sleep with me."

After a while, Xu Heng fell asleep.

I fell asleep when I fell asleep, and this hand was not honest.

Yue Pingting, "%￥#@@￥......"

孽 孽!

Why do you like such a big slob, and a stinky durian!

Yue Pingting was furious.

Neither did she.

What's more, she is also sleepy...

Hey……

sleep...

It was nine o'clock when the two woke up together.

Yue Pingting looked at Xu Heng with resentful eyes.

Xu Heng yawned, "What's wrong?"

"Knowingly asking!"

She blushed and picked up her notebook.

"Tell me about the movement of celestial bodies. This is the type of question I make more mistakes."

Xu Heng looked at Yue Pingting, seeing how serious she was.

"What time did you study last night?"

Yue Pingting, "Eleven o'clock...what's the matter?"

Xu Heng didn't continue joking with Yue Pingting.

If you make a joke at this time, you really don't know how to behave.

The reason why Yue Pingting worked so hard was for him.

Naturally, Xu Heng would not discourage her enthusiasm, but would encourage her instead.

　18 Thumbs up, leaning close to Yue Pingting's exquisite ear, and softly said, "Silly daughter-in-law, you are amazing now!"

Silly daughter-in-law! ! !

Silly daughter-in-law? ? ?

"Who, who is your stupid daughter-in-law! Don't talk nonsense! Xu Heng! You stinky...you are a big villain!"

Shy!

Xu Heng picked up Yue Pingting's notebook and looked it up.

"Listen carefully."

brush!

Yue Pingting immediately calmed down and pricked up her ears.

“F引=F向，G（Mm/r2）=m（v2/r）=mrw2=mr（2π/T）2=ma，这个你要牢记。”

"Through this, it can be concluded that V=root sign (GM/r), w=root sign (GM/r3), T=2π root sign (r3/GM), a=GM/r2."

"According to the above, we can know that the larger the radius, the smaller the linear velocity, the angular velocity is also reduced, and the acceleration is also reduced. Only the period T is increased. These can be seen at a glance."

Xu Heng wrote while Yue Pingting read.

"So, you can get a formula."

Yue Pingting, "The formula?"

She blinked her big eyes with a dazed look on her face, which was completely different from what she racked her brains yesterday.

And she had imagined in the morning how Xu Heng would teach her and from which aspect, but she was wrong.

Yue Pingting looked at Xu Heng like a sponge, eager to absorb the water of knowledge!

Xu Heng, "High orbit and low speed have a large cycle, and low orbit has a small cycle."

"The orbit is r, and the speed here is linear velocity, angular velocity and acceleration."

"do you understand?"

This is a knowledge point, and it was enough to memorize it by rote, but Xu Heng still listed the announcements for her, so that she can understand why it is so.

Yue Pingting nodded.

Compared with before, her comprehension has improved a lot.

It was as if he had opened his mind at once, and he understood faster and faster.

Xu Heng, "Okay, after we understand, let's look at the following..."

Yue Pingting, "Yeah."

"Expand what I just told you."

"We launch a geostationary satellite..."

right in bed.

Xu Heng was talking to Yue Pingting.

Zhou Xiu'e, who was passing by, stood in front of the door and listened attentively.

She looked happy.

Then walked away.

"From low orbit first, ignition acceleration becomes high orbit, and ignition acceleration again becomes the same synchronous orbit as the planet."

"Every time the ignition is accelerated, the function of the satellite becomes larger, which comes from the chemical energy of the fuel."

"So, high-orbit, low-speed, large cycle, big machine, big momentum, little kinetic energy!"

Yue Pingting was a little anxious, "I can understand the big machine, but what about the big machine?"

Xu Heng, "Height!"

Yue Pingting thought for a while and nodded.

"Because the speed is small, the high orbit is low speed, so the kinetic energy is also small."

After speaking, Xu Heng opened Yue Pingting's notebook.

"You recorded this question, so you know the answer?"

"Comparing the synchronous circular orbit and the near-Earth circular orbit, the answer is ready to come out, right?"

Yue Pingting's eyes lit up, "That's right, so choose A!"

"It's too fast! After reading the questions, you can get the answer in half a minute! Xu Heng, do you always answer the questions like this? It's so cool!"

With bright eyes, Yue Pingting stared at Xu Heng.

The corner of Xu Heng's mouth drew a line, "As long as you know a lot, there are thousands of ways to answer the questions."

Yue Pingting was happy. When she saw this kind of topic before, one head and two big, it might not be right to double-click there, but after Xu Heng said this, she suddenly understood.

"You are amazing! MUA~"

Hugging Xu Heng is just a mouthful.

But this time...

squeak...

The door was opened.

It was Zhou Xiu'e, "Ah..."

"My fault! My fault! Sorry!"

"I saw that you didn't get up. I prepared breakfast for you and wanted to bring it in for you. I let it go. I went out. I didn't see anything."

Yue Pingting blushed.

Huddled in Xu Heng's arms, not daring to lift his head.

Embarrassment to the extreme.

After Zhou Xiu'e went out, she closed the door for them.

Yue Pingting raised her head and looked at Xu Heng with a pitiful expression.

Xu Heng rubbed her head, "You took the initiative, so don't blame me for this."

Yue Pingting pretended to be crying.

Xu Heng bowed his head, "You girl, you did it on purpose, since you're like this, I'll..."

"Ah! Help! Xu Heng, you are a big dude, I still have questions, help me..."

"..."

After a lot of tossing, Xu Heng continued to talk about the topic.

"Launch a synchronous satellite: Accelerate in a low orbit to make it run along an elliptical orbit, and accelerate again when it reaches the apogee, so that the satellite can run along a synchronous orbit."

"There are two cutting points here, look..."

Xu Heng simply sketched the sketch, in order for Yue Pingting to understand it more intuitively.

"The tangential force is the same, the acceleration is the same, and the gravitational potential energy is the same!"

"However, the speed of the tangent point is different. If the trajectory is outside, the speed will be high, and if the trajectory is inside, the speed will be small."

"and also……"

"So, you're looking at your notebook while I get up and brush my teeth and wash my face."

Yue Pingting was still on the bed, holding her notebook and looking at it seriously.

She was still muttering.

"Really... I thought it would take hours to talk..."

"Hey... I've been working on a topic for a long time that I've saved up, and you're talking about it like this, and it's done so quickly!"

Yue Pingting was depressed.

What made her even more depressed was that she actually understood everything. Even if she understood it, she felt that it was very easy to do these questions now.

She began to suspect that she was still not herself!

I was not so smart before...

Zhou Xiu'e was not at home and went to the field. Yue Pingting came out and found Xu Heng who was brushing his teeth in the bathroom. She sneaked behind Xu Heng and hugged him.

This sweetness is worth MAX!

Xu Heng smiled slightly.

He suddenly remembered that time at school...

How long has it been!

It feels completely different!

Heavy!