Author: Zheng Zhongquan Wang … Article Source: Physics Teaching Discussion, No.2, 2005
After the Shenzhou 5 manned spacecraft independently developed by China was successfully launched in Jiuquan Manned Space City, many provinces and cities had questions about Shenzhou 5 in the senior high school entrance examination in 2004. It was later learned that Shenzhou VI would be launched in 2005. Compared with Shenzhou V, Shenzhou VI has three changes (the flight days must be more than one day, and there must be more than one astronaut on board. During the flight, astronauts will enter the orbital module to do space science experiments, and Shenzhou VII will also fly. Through the analysis of the senior high school entrance examination questions about "Shenzhou 5", we can get a preliminary understanding of shenzhou spaceship's knowledge, so as to solve such problems in future exams.
Typical example (1)
1. (Harbin, 2004) In June 2003 10, China successfully launched Shenzhou 5 manned spacecraft, which left the launch tower with the rocket and flew into space. The following statement is incorrect.
A. the spacecraft is subjected to a balancing force.
B. the rocket thrust does work for the spacecraft.
C. the kinetic energy and potential energy of the spacecraft are increasing.
D. the chemical energy of fuel will eventually be converted into the mechanical energy of the rocket.
2. (In 2004, Heilongjiang Province) Shenzhou 5 spacecraft successfully completed its first manned space flight, realizing the space dream of China people. When the spacecraft flies around the earth, if the following experiments are carried out in the cabin, what cannot be completed is
A. measure the quality of ore samples with a large flat plate.
B. observe the onion skin with a microscope.
C. use temperature training to measure temperature.
D. use the spring force measurement to train the monetary force of the object.
3. (Jiangxi Province, 2004) June 65438+10/October 65438+June 2003, Shenzhou 5 manned spacecraft successfully returned home, realizing China people's dream of flying for thousands of years. When the spacecraft slowed down and landed, "space hero" Yang Liwei's
A. With the increase of kinetic energy, the potential energy of monetary power decreases.
B. kinetic energy decreases, and potential energy of monetary power decreases.
C. the kinetic energy remains unchanged, and the potential energy of monetary power remains unchanged.
D. the kinetic energy is constant, and the potential energy of monetary power decreases.
1 related knowledge
Shenzhou 5 was launched by China's Long March II F high-thrust carrier rocket. Rocket is the basic power device of human space activities. When the rocket engine is working, fuel and oxidant burn in the combustion chamber to produce high-temperature gas, which is injected backward at high speed through the nozzle, generating thrust for the rocket to launch. The chemical energy of fuel is converted into internal energy, which in turn is converted into mechanical energy of rocket.
Spacecraft will be subjected to various forces (such as the gravity of the earth, the thrust of fuel combustion, etc.). During the whole space flight, the movement made by the rocket after liftoff is mechanical movement. In the ascent stage, the spacecraft accelerates under the thrust of the rocket. At this time, astronauts have to bear 4-5 g (g = 9. 8N/ kg) is "overweight", which means that four or five people like him are on him. When the spacecraft enters the orbit around the earth, it is only influenced by the gravity of the earth, making it turn around the earth and enter a state of weightlessness. Students rush down from the top on a roller coaster, which is similar to weightlessness.
From launch to successful return, the spacecraft completes hundreds of operations in space, that is, by injecting gas to change the orbit and adjust the attitude (that is, change the flying height and running direction), and applies the principle that force can change the motion state of objects in physics. When the spacecraft returns, it needs to apply force in the opposite direction (start the reverse rocket at this time) to slow down and make the spacecraft fall back to the ground.
2 related data
"Shenzhou 5" circled the earth 14 R, lasted 2 1h, and had a voyage of 600,000 km. After liftoff, the spacecraft entered an elliptical orbit with a perigee height of about 200km and an apogee distance of about 350km from the earth's surface, and entered a circular orbit with a variable track pitch of about 343km from the earth's surface.
3 example analysis
In the example 1, the spacecraft is launched by rocket thrust, and it is impossible to be acted by balancing force when accelerating. At this time, the kinetic energy and potential energy of the spacecraft are increasing, and the increased mechanical energy is converted from the chemical energy of rocket fuel, so D is chosen. In example 2, if you do experiments in the cabin, you can't measure the mass with a balance or the gravity of an object with a dynamometer (but you can measure the hand tension with a dynamometer) because of weightlessness, so the answers are A and D. In example 3, when the spacecraft returns, it has started the reverse rocket to reduce the speed, kinetic energy and gravitational potential energy, so you choose B.
Typical example (2)
4. (In 2004, Dalian Experimental Zone for Curriculum Reform) From June 5438+1October1May to June 16 in 2003, China successfully launched and recovered Shenzhou 5 manned spacecraft.
(1) When the rocket was launched, the high-temperature flame sprayed downward, and a large amount of "white gas" gushed out from the large pool at the bottom of the launch pad. How are these "white gases" formed?
(2) When the return capsule returns to Earth, the altitude is 1. 2 m from the ground, the recoil engine fired at the ground, and the spacecraft slowed down further and finally landed. Please write down two mechanical knowledge involved in this process.
Article 1:
Article 2:
5. (Liaoning Province, 2004) As shown in Figure 1, at 9: 00 on June 65438+1October 5, 2003, China's self-developed Long March II F rocket successfully rose into space with Shenzhou 5's manned spacecraft, and then circled the earth several times, and on June 65438+1October 65433.
( 1)
(2)
1 related knowledge
There is a large pool at the bottom of the rocket launch pad. When the rocket is launched, the water in the pool will vaporize into steam when it meets the high-temperature flame, and the high-temperature steam will liquefy into small water droplets when it meets the cold, forming white gas. When the rocket flies in the atmosphere, friction generates heat, mechanical energy is converted into internal energy, and the head temperature can reach several thousand degrees Celsius. In order to prevent the rocket from burning out, the rocket head is coated with a special material, which melts, vaporizes and absorbs heat at high temperature.
As the spacecraft leaves the launch vehicle and goes into space smoothly, the unfolded solar panels (solar wings) are like two pairs of huge wings growing on the spacecraft. Solar panels have two functions of charging and power supply, which is equivalent to a small power station. By converting solar energy into electric energy, it provides energy for the electrical equipment on the spacecraft. Although the spacecraft is equipped with emergency power supply, its support time is limited, and it mainly relies on solar panels to provide electricity.
After the spacecraft enters the orbit, every time it flies around the earth, it will pass through the sunshine area for one hour and the shadow area for 30 to 40 minutes, so the outer surface will at least undergo the temperature difference test of 180℃. When the spacecraft returns to the capsule, it is often seen that the outer surface is ablated, which is caused by the spacecraft entering the atmosphere at high speed and rubbing with the atmosphere (the temperature can reach 2000 degrees Celsius). The ablation material used in the return capsule can undergo physical and chemical changes such as decomposition, melting, evaporation and sublimation at high temperature, which makes a lot of heat taken away by the mass consumption of the material, thus preventing heat from flowing into the return capsule. Commonly used ablative materials include PTFE, graphite, carbon and carbon composites, aging and glass materials and reinforced phenolic materials.
The launch time of "Shenzhou" series is selective. The launch time from Chang 'e I to Chang 'e IV is at night, which is mainly for the convenience of optical tracking and measuring instruments on the ground to easily capture the target when the spacecraft is launched. The Shenzhou 5 spacecraft is the first manned flight. In order to fully protect the safety of astronauts, the launch time was chosen during the day.
The structure of the Long March II F rocket is shown in Figure 2.
3 example analysis
In example 4. (1) There is a big pool at the bottom of the rocket launch pad. When the rocket is launched, the water in the pool is vaporized into steam when it meets the high-temperature flame, and the high-temperature steam is liquefied into small water droplets when it meets the cold, forming white gas. (2) ① The forces between objects are mutual; ② Force can change the motion state of an object. Example 5: When rocket fuel burns, (1) chemical energy is converted into internal energy; (2) The rocket head is pointed to reduce air resistance; (3) During the ascent of the rocket, internal energy is converted into mechanical energy; (4) The special material of the rocket head melts at high temperature and vaporizes to absorb heat. Protect the rocket head from excessive temperature; (5) A large amount of white gas is generated at the bottom of the launcher, which is vaporized and liquefied; (6) The astronauts are overweight during the accelerated ascent; (7) Astronauts are in weightlessness after entering orbit; (8) Solar panels in the air convert solar energy into electric energy; (9) The recoil principle is used for ascent, descent and orbit change; (10) Yang Liwei can't go out for extravehicular activities without a spacesuit and only an oxygen bottle, because there is no atmospheric pressure (or the space temperature is too low) for extravehicular activities. (1 1) When the return cabin descends to 80 km, it burns red outside the cabin due to the friction between the cabin and the air, resulting in high temperature, but the temperature inside the cabin has not changed due to the good thermal insulation performance of the cabin material; (12) "Shenzhou 5" was launched in the daytime to make full use of solar energy. After the spacecraft enters space, photovoltaic cells convert solar energy into electric energy to maintain the normal work of the spacecraft.
Comments: The senior high school entrance examination often has questions that combine new scientific and technological achievements. These questions are high-minded, low-lying, with new information and obvious flavor of the times, aiming at guiding students to care about the development trend of science and technology, social progress and love scientific knowledge. We should try our best to expand our knowledge and make full use of what we have learned to reason and solve practical problems that we have never been exposed to.