Become a master from now on

Chapter 320 Shenxiu (please subscribe and ask for a monthly pass!)

Fang Chao answered quickly, and within a short while, he had already completed the fourth sub-question of the second part.

4 (10 points) In winter in northern my country, even if the temperature is very low, the water in some deep rivers, streams, lakes, and ponds will generally not freeze to the end, and fish can survive the winter safely when the water surface freezes , try to explain why water does not freeze to the bottom.

For physics competitions, most of the questions are common in daily life. It does not require a huge amount of calculation like mathematics, and even requires you to draw a lot of auxiliary lines. Therefore, some famous schools are more willing to recruit students. It is the people who have excellent results and performances in IMO events, because their thinking is more groundbreaking.

Of course, this does not mean that no one cares about physics competitions. Some outstanding students will still be recognized by prestigious schools, and there are also admissions offices of some prestigious schools who come here to check out excellent physics talents.

Fang Chao quickly finished most of the fourth question.

In autumn and winter, the temperature begins to drop, and the upper layer of water in rivers, lakes, and ponds becomes colder first, becomes denser and sinks to the bottom of the water, forming convection. When the temperature reaches 4°C, if the temperature drops again, the upper layer of water expands and becomes less dense. , the convection stops, 'floating' on the water surface, forming a 'cover', and the water below loses internal energy mainly by heat conduction, but because water is a poor conductor of heat, the heat dissipation is relatively slow.

The temperature of the surface water drops to 0°C before the water below, and it starts to freeze. The density of ice is smaller than that of water, so it always floats on the water without sinking. The temperature of the water under the ice is from 0°C to bottom. 4°C, if the temperature is lowered, it will gradually freeze from top to bottom.

Due to the slow upward heat dissipation through heat conduction, and the ground heat is conducted upward from the bottom, the freezing speed is slow. As long as the temperature is not too low or the low temperature time is not long, and the water in lakes and ponds is deep, the water will not If it is frozen, the ice will not freeze all the way to the bottom of the water.

The physics question itself does not require a lot of data to implement. It is more reflected in the bits and pieces of life, not as complicated as mathematics. As long as you know the various changes in it, you can easily answer it. .

Fangchao's LV3 physics level allows him to deal with things that are not some advanced aspects such as quantum mechanics and electromagnetism, but just common sense in life, so he is definitely capable of dealing with them easily.

"Tsk tsk, the four questions of the short-answer questions are not too difficult, and I will give you a fifth question, which is not worth points anyway, but it feels uncomfortable to be empty. Even if you get No.1, someone will keep pace with me. But they finished all the extra questions, but I left them empty, so this No. 1 is somewhat unworthy of the name."

"Harmful……"

Defenses can not do without.

Fang Chao was on guard, but how could he know that there are very few perverted people like him in this world, besides, it only took him 23 minutes to finish the first part and the second part, and the rest It's just the last third part.

After completing the two parts, Fang Chao raised his head and glanced at the people beside him and behind him, and found that most of them were deep in thought, and some were writing over there, seeming to be stuck in a difficult problem.

"Is there a problem here?"

Fang Chao was stunned for a moment, it shouldn't be, these are simple basic operations, aren't they?

He even had some doubts, did the boss who set the question this year specially open the back door for the candidates, but he shouldn't...

An invigilator saw Fang Chao staring at him for a while with a "thiefy" look, and thought, thinking about cheating at this time?

So he walked unsteadily near Fang Chao, wanting to see how far this student had finished, whether he had just done a few multiple-choice questions, but when his eyes fell on Fang Chao's physics test paper, Time couldn't help but froze for a moment.

Have you done all the multiple choice questions?

So fast?
Are you blind?

Don't you need to calculate?
Although some physics questions are easy to answer, there are also some questions that require a small range of calculations to get the correct answer. There is no place for a draft on the other party's test paper, which really makes the invigilator very suspicious .

His eyes quickly swept over some of the multiple-choice questions, but the look of suspicion on his face was even stronger.

copied?

Because he found that there were no mistakes in the multiple-choice questions of the questions he was looking at. Even if it was a multiple-choice question, he had screened out all the correct answers. For the answers to the multiple-choice questions he knew, the other party had no mistakes in any of the questions.

Should not be ah.

I'll look at the short answer questions again.

His eyes once again fell on the second part of Fang Chao's physics volume.

When he saw this, he was shocked again.

What?
Five short answer questions?

You answered all these f---ing things?Moreover, the answers written for each question made it impossible to pick and choose the questions.

If you only answered four questions, I have nothing to say, but you have already answered four questions, and now you don't even miss the fifth question?You want to answer all the questions in the test paper...

This is so special!

Feelings: You were looking around all over the place just now because you were tired from writing and wanted to relax?
Are you a pervert?

The invigilator had mixed feelings in his heart. Looking at the other contestants, many were still on the multiple-choice questions. Even some of the fast ones had only reached the second question of the short-answer questions. But what about this contestant? ?He has already solved all five short answer questions.

People are more mad than people.

This player may be a dark horse in the physics competition.

After relaxing for about 2 minutes, Fang Chao quickly devoted himself to answering the third part of the physics competition.

For the same five questions, candidates only need to do four small questions, each with 15 points, totaling 60 points.

The first three questions are mandatory questions, and the last two questions are optional. If you choose the fourth question, the fifth question will not be included in the total score. If you answer both questions, the fourth question will be used as the optional question for scoring .

question.

The air storage tank of the submarine is connected with the water tank. When the air in the air storage tank is pressed into the water tank, the water tank will discharge water to make the submarine float. The volume of the air storage tank of a certain submarine is 2m, and the barometer on it shows that there is Compressed air with a pressure of 2x10 to the seventh power Pa, use the compressed air in the cylinder to discharge the water with a volume of 10m in the water tank to the submarine’s water tank during the floating operation after diving to the bottom of the sea. At this time, the barometer shows the remaining air in the cylinder The pressure is 9.5x10 Pa, assuming that the temperature of the compressed air is constant during the drainage process, try to estimate the depth of the seabed where the submarine is located.

(End of this chapter)