The two physics questions in front of him did surprise Fang Chao a little, but the more challenging things were, the more he wanted to try.

For top students, isn't solving one problem after another just like those foodies discovering new food? The scent, the color, and especially the thrill of being part of your body in your stomach.

It's really like flying into heaven.

"Teacher Zheng, give me some time and let me unravel it for you to see."

Fang Chao raised his head and looked at Zheng Zhiqiu.

Zheng Zhiqiu glanced at Fang Chao and said, "It's okay, you continue to do your questions, I won't bother you, I'll watch the news." ”

Zheng Zhiqiu has the habit of paying attention to the news on weekdays, the school will subscribe to the newspaper for the teachers of each year, it is the fresh newspaper of the day, it is not an exam now, there is no need for him to stare at Fang Chao to answer.

When Fang Chao heard this, he completely devoted himself to the two physics problems given to him by Mr. Zheng.

This takes into account the problem of the projectile angle, when the projectile angle is small, the motion time is shorter, but the horizontal velocity is larger, on the contrary, the motion time is longer but the horizontal velocity is smaller, so it is entirely possible that they have the same range, by the decomposition of the motion and the characteristics of the horizontal motion...... The idea of solving this problem is given.

After Fang Chao figured out the idea of solving the question, he began to write without the slightest hesitation.

He was the first to draw a plane Cartesian coordinate system on the x-axis and y-axis in a blank space, the origin of which is the projectile point, and began to list the equations.

Solution: For any projectile there is

x=v0cosθ*t

y=v0sinθ*t1/2*gt??

From this, the equation of the trajectory of the ball was obtained, and Fang Chao deduced it.

Such a problem is divided into two modes of motion, one is a uniform deceleration linear motion in the vertical direction, and the other is a uniform direct motion in the horizontal direction.

It is precisely because Fang Chao understands this point that he knows the problem of this question.

I have to say that this question is quite interesting, it is not easy to solve it, if it is not for the physical level to be improved to LV2, Fang Chao may need a long time to solve this question, at least tonight, maybe he will have to consult Teacher Zheng.

When y=0, solving x is the horizontal range.

So x=v0?? sin2θ/g

Thus the ball movement time T is obtained.

Since the two balls A and B have the same range, there is

sin2θA=sin2θB

Therefore, 2θA = π-2θB

At this point, the next steps are pretty much a logical one.

Fang Chao wrote a few more equations.

So the final answer to this question was obtained.

The time for ball B to travel in the air is √4v0?? -（Tag?? ）/g

"Ice Fruit!"

"That's it!"

Fang Chao breathed a long sigh of relief and looked at the time, it took 21 minutes.

It's not fast, but it's certainly not slow.

In terms of Fang Chaocai's physical level of LV2, it is still necessary to consume some brain cells to deal with such a problem.

But overall, the effect is still good, both in terms of steps and answers, it is very unsatisfactory.

Fang Chao's long sigh of relief was captured by Zheng Zhiqiu, and he immediately put the newspaper aside and asked, "Finished answering?" ”

"Solved the first question, Mr. Zheng."

"So fast?"

Zheng Zhiqiu was stunned for a moment, this question already has the medium difficulty of the physics competition, if the normal object contestant wants to answer, I am afraid it will take more than half an hour, but Fang Chao took a total of ten or so minutes from the examination to the end of the answer, which really surprised Zheng Zhiqiu.

He folded the newspaper and put it aside, and then said directly, "Show me the answer to your first question first." ”

"Huh? Teacher, I haven't done this second question yet. ”

"I think what does your first question have to do with your second question? Hurry, don't ink. Zheng Zhiqiu urged.

Fang Chao handed the answer to the first question to Zheng Zhiqiu, "Teacher Zheng, here you go." ”

After receiving the manuscript handed over by Fang Chao, Zheng Zhiqiu continued, "What are you looking at me for? Look at the question, do the second question. ”

Fang Chao: "......"

Mr. Zheng, it's so difficult for you to communicate.

I thought you would talk to me about the first question, but you just asked me to do the question, so cold, ruthless, and vexatious.

So Fang Chao obediently began to do the second question.

The second question already deals with astrophysics.

"Hmph."

Fang Chao snorted lightly, ready to show his strength.

"What are you humming?" Zheng Zhiqiu raised his head and looked at Fang Chao with some displeasure, this is not a good habit.

"No, teacher, my nose is stuffy, this hum twice to breathe."

"Hurry up and do the question."

"Oh."

Fang Chao didn't even dare to hum, Physics Teacher Zheng was too terrifying, a majestic aura permeated, like a mountain suppressing it, Fang Chao was so frightened that he trembled, he could only do the question to relieve this pressure.

Hey, I can only give you 2 stars of difficulty for this question.

It's not exciting enough for the first question.

Barely able to plug between your teeth.

I'll take care of you!

Three minutes later, Fang Chao was in his hands.

When the Earth orbits the Sun, it is derived from the law of gravitation and Newton's law

GMsMe/R?? =Me（2π/T）?? r

where G is the gravitational constant, Me and Ms are the masses of the Earth and the Sun, r is the distance between the Sun and the Earth, and T is the orbital period of the Earth.

Let θ = 2Rs/r

GMs/Rs cubic = 8 (2π/T)?? (1/θ) cubic

For an object with mass m at the earth's surface, GMem/Re?? =mg

where Re is the radius of the earth, and 2πRe=360l according to the title

Substituting the formula GMe/Re cubic = πg/180l

Let ρs and ρe denote the density of the sun and the earth, respectively

ρs=Ms/(4/3)πRs cubic, ρe=Me/(4/3)πRe cubic,

ρs/ρe=gT?? θ?? /180l*32π=3.92。

"Done, done!"

Fang Chao put down the pen and shook his right hand to write, it was so sour, writing two questions in a row was still so frequent, so that his right hand entered a load state, mainly because he didn't stop writing at the end of the day, and he didn't have a good rest this night, and he immediately felt that he would be tired from reading.

But compared to the joy after answering the question, this fatigue is nothing at all.

Zheng Zhiqiu had just finished reading Fang Chao's first question, and he had nothing to say about Fang Chao's first question, because it was completely correct, both in terms of steps and solution ideas, it was very perfect, so that people couldn't find fault with it, and it was also very difficult to say it from the handwriting, Fang Chao was different from ordinary students, his level of calligraphy was also very high, and the whole question made people look extremely pleasing to the eye, without any irritability, just like looking at a work of art.

But after Fang Chao put down the pen at this moment, he stared at Fang Chao and said, "Are you done again?" ”

()