At this moment, Wu Bin was already sitting on the bus to Xianghai Middle School, which was the venue for this physics competition.

There were a total of ten participating students on the bus, including Wu Bin, and at this moment, Wu Bin, who was sitting alone with a book, was a little isolated.

But this is normal, among the other nine people, Zhang Qiu is the one who is most familiar with Wu Bin, but the most effective relationship between the two is that they are classmates in the same class, oh, and they have also done duty together.

But Zhang Qiu and the other four high school juniors are all old friends, they have participated in the competition together since the beginning of high school, gritted their teeth and persevered all the way to the present, which is an absolute comradeship.

There are four left, two of them are freshmen of high school, and they are estimated to be practicing soldiers, so they naturally sit together, and the other two sophomores of high school can be regarded as initially establishing a comradeship, and they are chatting about what exam questions will most likely come out this time.

"Nervous?"

Seeing Wu Bin sitting alone, Bi Wanqing sat down next to him and asked.

"It's good that both teachers have so much confidence in me, what else do I have to be nervous about." Wu Bin closed the book and replied.

Bi Wanqing smiled after hearing this: "Your logic is also a little reasonable, so have you done everything after passing the preliminaries?" ”

"Well, I try to make up all the other subjects within a week, anyway, there is no problem with the teachers of each subject."

The study plan Wu Bin has basically been arranged, according to his current progress, it is not difficult to complete, and after passing this physics competition, his experience is almost enough to upgrade, and the new talent points will allow him to further improve his learning speed.

Of course, it would be perfect if there was another draw.

"You're so confident...... It's a bit like when I was younger. ”

After speaking, both the teacher and the student laughed.

While the teachers and students were chatting, the bus soon arrived at the destination and stopped at the door of Xianghai Middle School.

Then, according to the instructions of the staff, Wu Bin quickly found his own classroom, and coincidentally, Zhang Qiu was sitting not far from him.

"Come on."

The two of them exchanged a word of encouragement and sat down.

Then the invigilator reads out the various examination room disciplines and distributes the papers.

As soon as the volume was in his hands, Wu Bin scanned the title on the paper, and finally came to the conclusion.

‘funny’

Wu Bin, who finished scanning the questions, could see that the questions on this paper were very polarized, and four of the five multiple-choice questions were "people with a little foundation in high school physics can answer them." ”

The first question is a physics general knowledge question, the second question is a simple heat exchange in heat, and the third question is ...... This is a language question, right?

The fourth question, the test is light intensity, which is beyond the scope of high school, and it is estimated that the difficulty is a bit big if you haven't learned it, but if you have learned it, it is trivial.

The only difficult thing is the fifth question, because the elliptical orbit brings some calculation difficulties and thinking difficulties, which is a bit torturous, but for Wu Bin, it is okay, and he is quite good at the problem of brainstorming after some hard practice.

Then there is the fill-in-the-blank question, one is simple harmonic vibration, which uses the classical model, and can be easily answered with the simple vibration dynamics equation.

The other two fill-in-the-blank tests are optics, a secondary optical axis and a Young's double slit, both of which are basic knowledge in optics.

At this point, there are really no particularly exciting questions, and the last is a big question, and the few questions to get started are not too difficult.

Among them, there are two courses in electricity, one is to turn the coil, the foundation of the foundation, and the other is the calculation of the Hall coefficient, the type of problem Wu Bin has really not seen, but it is not too difficult, a few troublesome calculations are quickly solved with a calculator.

But the final finale mechanics question, which is really a sudden change in painting style, is the most polarizing question in the volume that Wu Bin thinks.

The title goes like this.

An artificial satellite with a mass of m = 3000 kg moves in a circle around the earth at an altitude of H = 180 km above the ground, where the gravitational acceleration g = 9.3 m · s minus 2 square due to the action of air resistance, the altitude of the artificial satellite will decrease in one year ΔH = 0.50 km. It has to do with the shape of the object. When the satellite is operating at high altitude, it can be considered that the drag coefficient of the satellite is C=1, and the maximum cross-sectional area of the satellite is A=6.0m².The radius of the earth is known to be R0=6400km.

This is the finale of the gravitational question, and the requirement is to estimate the density of the atmosphere around the satellite using the data given in the question.

But this question, in fact, can be regarded as hitting Wu Bin's muzzle, the difficulty of this question Wu Bin can see that the candidate needs to find the correct outstanding elements, ignore the secondary factors, and then make a reasonable estimate, that is, the ability to read the question, that is, the battlefield where the abstract thinking ability can exert the greatest energy!

And what does this salient element refer to?

Since the question requires an estimate of the atmospheric density at which the satellite is located, known from F=12pACv², p is required.

That's looking for the relationship between F and v, so it's clear that it's a matter of functional transformation.

After you have an idea to solve the problem, it's easy, the formula! Columns are it!

Solution: The velocities of satellites around 1 year are v1 and v2 respectively, according to the law of gravitation and Newton's law

Mm/1² of GR=v1²/R1, (R1=R0+H)(1)

Mm/2² of GR=v2²/mR2(R2=R0+H-ΔH)(2)

The idea is there, the formula is listed, and the rest is pushed, but there is quite a lot of mechanical knowledge involved, and the process is quite difficult.

After solving it, Wu Bin let out a sigh of relief.

"Your sister, there are so many pitfalls, calculus is still bitter if you don't learn it, otherwise the force F in the problem is a variable force, which can be solved by calculus." ’

But it's also a pit, I'll just figure it out anyway." ’

After relaxing for a while, Wu Bin looked around and found that the originally full classroom had already seen a lot of people leave.

'I'm rubbing??? Competitors scary? This question is quite difficult, do you do it all so quickly? Does this mean that the preliminaries are not difficult for them? ’

'It looks like there are a lot of masters in the semi-finals. ’

After thinking about it, Wu Bin looked in the direction of Zhang Qiu again, and found that he was still there, and he kept scratching his head with his pen, looking uncomfortable.

'I guess I've solved the last question, Amitabha, come on.' ’

Originally, Wu Bin thought about handing in the papers, but when he thought that he didn't put pressure on Zhang Qiu to hand in the papers this morning, he thought about it, anyway, it was not bad for this little time, and then try to solve the two electrical problems in other ways.