Chapter 18 The National Finals Begin
After running a few laps, Xu Chuan walked slowly to the Songlin Canteen of P University.
It specializes in a variety of steamed buns and porridge, making it a great place to have breakfast.
After buying some breakfast items such as pan-fried buns, meat buns, and soy milk, Xu Chuan went back to his dormitory while eating. At this time, his teammates were also getting up, some were napping, and some had already finished washing.
"Breakfast is here, everyone come and eat."
Xu Chuan placed the fried buns and soy milk on the table.
"Thank you, Brother Chuan."
"Fried buns, I love them."
"Brother Chuan, thank you for your hard work."
“Where are the fried dough sticks, Brother Chuan, there are no negative comments about the fried dough sticks!”
“Where’s the bean juice? There’s no special bean juice!”
Hearing about the breakfast, the dormitory immediately became lively. Everyone swarmed over and divided the breakfast on the table.
Xu Chuan smiled. Songlin Canteen sells bean juice, but I am afraid that except the locals, no one else can eat it.
And after eating a bowl of bean juice, no one in this dormitory may need to participate in today's competition.
After breakfast, the group headed to the competition venue.
The national finals of the physical competition are proposed and evaluated by the National Competition Committee. Each final has about 50 first prizes, about 80 second prizes, and about 100 third prizes.
In addition, there are individual special awards such as the best overall performance award, the best theoretical performance award, the best experimental performance award, and the best female student performance award.
The number of people sounds a bit large, but in fact it accounts for almost half of the participating students. Just like this year, the total number of students participating in the national finals is about 500.
However, students who can participate in the national finals can be said to be strong, and awarding awards to these students is not a problem.
After the routine inspection, Xu Chuan entered the examination room.
The finals of the physical competition include theoretical and experimental parts. The competition time is 3 hours each. The full theoretical score is 280 points and the experimental score is 120 points. The organizing committee hires university teachers to mark the papers.
The theoretical examination time is from 8:30-11:30 in the morning, and the experimental examination is from 14:00-17:00 in the afternoon.
Entering the examination room, the test papers were handed out. Xu Chuan checked them over after getting the questions.
There are four theoretical questions in this year's national finals, each worth 70 points. Each question has at least three questions below it.
It takes three hours to answer these four questions, which is quite difficult. According to the usual finals, more than half of the students cannot finish these four questions in three hours.
But this is used to select talents, so it is normal to be difficult.
After all, everyone can get perfect scores, so how can we tell who is stronger?
Therefore, there are very few people who get full marks in the national competition in the physical competition, and there may not be one in a year. Xu Chuan didn't think too much. After checking the test paper, he looked at the questions.
Question 1 (64 points)
In June 2014, the "CZ-2C" carrier rocket took off and successfully docked with the space station. This involves the issue of the pursuer ("CZ-2C" carrier rocket) and the target (space station) meeting in orbit around the Earth.
This question uses the Holman orbit change scheme to explore how the pursuer changes speed (speed and direction) to achieve docking (encounter) with the target on the fixed orbit.
As shown in Figure 2a, both target A and pursuer c move counterclockwise at a rate n on a circular orbit with radius ro. At time 0, their positions are 0A; = 0o, 0i=0, rA; = rai= ro;
At this moment, the pursuer c ignites instantly, and the speed changes instantly by Δ (as shown in Figure 2b); the orbit of c also changes from radius r. The circular orbit instantly changes to the elliptical orbit shown in Figure 2c, with the long axis and polar axis directions of the elliptical orbit.
Target Aro Chaser c Center Figure 2aVo+Ava Chaser cAv Elliptical orbit Circular orbit.
Question 1 (10 points): If the mass m of the flying object, the energy E (actually the total mechanical energy of the system composed of the flying object and the earth) and the angular momentum L are all known quantities, try E, L, m and the values given in the question The parameters To, 2o, etc. are known to represent the orbital parameters R, ε.
It is known that the form of a positive elliptical orbit (the long axis is along the polar axis direction) in the polar coordinate R coordinate (the origin is taken as the right focus) is r (6) = 1 + ε cosφ, where R is the orbit size parameter and is the orbit eccentricity rates, collectively referred to as orbital parameters.
Second question (6 points): Write the expression for the orbit Rc(0c) of the pursuer c after ignition (see Figure 2c), expressed in terms of ro, eccentricity ε and φ.
Question 3 (6 points): Write down the ratio Tc/Ta of the orbital period Tc of pursuer c to the orbit TA of target A after ignition, represented by ε and φ.
Question 4: (18 points) Define two ignition parameters (see Figure 2b): the dimensionless velocity changes the angle α between δ=|△υ/υ0|, (when overlapping, α=0, clockwise (taken as the positive direction), use the ignition parameters δ and α to represent the eccentricities ε and εcosφ of the orbit of the pursuer c.
Question 5 (9 points): Consider the situation where the pursuer c and the target A meet at the first-type orbit converging point (see Figure 2c). Suppose that the number of times that target A passes the first-type orbit converging point since time 0 is nA, The number of times pursuer c passes through the first type of orbit rendezvous point.
Question 6 (3 points): Express nA with 8 and α, fix 8, and try to find two simple changes of function nα (α) relative to α.
Question 7 (12 points): If one of the above two α0 values is taken.
(1) There is an upper limit for δ value, find.
(2) Let the initial value of φA be
"It's still a familiar topic and a familiar recipe."
The first big question came into his eyes, and Xu Chuan touched his chin with interest.
After the title came into view, the vague memories buried deep in his brain struggled to revive, giving him a slightly familiar feeling.
Wu Jing is too far away from who he was before his rebirth, and the huge memory generated in twenty years is enough to bury these past events.
Even he is still unable to remember the specific questions, but he can still remember the general scope.
Although there are only four major questions in the National Finals of the Wushu Competition, the first big question involves transporting rails to hold down the building. This precipice is a disincentive to the participating students.
One question, seven questions, no, it should be said eight questions, the difficulty is so high.
Normally, the first question of the Wu Jing National Competition usually only has four short questions, and the difficulty is not very high.
But this year's first question is probably no less difficult than the finale question in previous years.
"Are you going to show off your power when you come up?"
Thinking about it, Xu Chuan looked up at the examination room.
As he expected, many students in the same examination room were a little stupid, looking at the test papers blankly, and some frowned, and the signature pens in their hands slid unconsciously on the paper.
Those who can reach the national finals are basically senior high school students and competition students. This means that all students have done the competition questions in previous years. Regardless of whether they can do it or not, at least they have seen the questions and format.
At this point, we directly moved the rails to calculate the town building, which indeed confused a lot of contestants, leaving many students at a loss of how to answer the question for a while.
(End of chapter)