Urgent need: national 100 school unit test demonstration volume and physical volume (10) comprehensive test answers of "gravity and aerospace"

The latest intensive training questions of the national junior middle school physics knowledge Olympic competition (2)

1. The TV can be turned on and off with the remote control. The remote control is used to control the TV: ().

A. red light B. infrared light

C. violet light D. ultraviolet light

2. When cooking, if you accidentally splash water droplets into the hot oil pan, you will hear a beep and the oil will splash out. The main reasons for this phenomenon are: ().

A. water is a poor conductor of heat. B. the temperature of water droplets is different from that of oil.

C the boiling point of water is lower than the temperature of hot oil. D. the specific heat capacity of water is higher than that of oil.

In the children's playground, the photographer took pictures of cartoon characters. When focusing, he found the position of cartoon characters on ground glass as shown in Figure A ... In order to make the position of cartoon characters on ground glass as shown in Figure 1B,

Photographers should be appropriate: ().

A. move to the lower left

B. Move to the lower right

C. Move to the upper left

D. Move to the upper right

4. The picture shows four kinds of control circuits of stair lighting designed by Xiaoming, in which S 1 and S2 are upstairs and downstairs switches respectively (both are single-pole double-throw switches). You need to toggle any switch to change the original lighting or extinguishing state of the light. The best scheme in practical application is: ().

5. At the bottom of the aluminum pot used for boiling water, there are often several uneven concentric circles, whose main functions are:

( 1)_______________________________________;

(2)_______________________________________。

6. Xiaofeng's height is 1.70cm, his eyes are 8cm above his head, and he stands upright on the horizontal ground and looks at the mirror. If he wants to see his feet from the plane mirror hanging vertically on the wall, the height of the bottom of the mirror from the ground should not exceed _ _ _ _ _ meters.

7. Xiaoming's electric energy meter nameplate is marked with words such as "220V", "5A" and "3000r/kw.h". If electricity is used continuously for a long time, his family can use electrical appliances with a total power of _ _ _ _ _ _ _ _ _ watts at most; Every turn of the dial of the watt-hour meter 1 means that his home has lost _ _ _ _ _ J's electricity again.

In the spring of 2003, SARS appeared in some cities in China.

In the epidemic, sprayers are widely used for disinfection in public places. Tugai

The schematic diagram of a sprayer is given and its working principle is introduced.

Physical knowledge (write only two items):

( 1)_____________________________________;

(2)_____________________________________.

9. On June 6, 2003, at 6: 54, 10, 16, Shenzhou 5 successfully completed the first manned space flight in China, and the return capsule landed safely at the main landing site in Inner Mongolia.

(1) The energy conversion during rocket launch is mainly _ _ _ _ _ _ _ energy into _ _ _ _ _ energy.

(2) When the spacecraft flies around the earth after turning off the engine, if the following experiments are carried out in the cabin, the most difficult thing is _ _ _ _ (fill in the blank): a. Measure the temperature with a thermometer; B, observing the onion skin with a microscope; C, filtering with a funnel and filter paper to remove the sediment in the water.

(3) If crop seeds are carried into space and then brought back for planting experiments. The purpose of this is _ _ _ _ _ _ _

___________ ________。

10. The electric hotbed is one of the hotbeds commonly used for seedling raising in early spring in northern China. The manufacturing method of the electrothermal hotbed is: firstly, dig the bed soil about 20 cm thick, lay a layer of wheat straw or sawdust under the bed, and then lay a layer of plastic film. Spread the heating wires evenly on the plastic film with the spacing of 10cm, and then put the bed soil back, so that the electric hotbed is ready.

The thermostat of the electric hotbed is equivalent to a variable resistor, and its resistance changes with the temperature. It can automatically control the current through the heating wire according to the temperature, so as to realize the automatic control of the hotbed temperature. When using, please connect the thermostat with the electric hotline. The electric hotline must not be knotted, crossed or overlapped, otherwise it may be dangerous due to _ _ _ _ _ _ _ _ _. This method is to use _ _ _

_ _ _ _ _ _ _ _ _ Get the temperature suitable for seedling growth.

1 1. The design scheme of a city railway station is shown in Figure 4. The entrance and exit tracks and platforms form a gentle slope. What are the advantages of this design from the perspective of energy utilization?

12. On the side of ocean-going ships, several "load lines" are drawn. When the ship is fully loaded, the water surface cannot exceed the specified load line. The picture shows an ocean-going ship and

Schematic diagram of load line, marked with

W is the North Atlantic load line, standard

The one with S is the Indian Ocean load line. transport

Analyze with the physical knowledge you have learned.

What does this sign mean?

13. The front windshield of cars has a certain inclination angle, while the front windshield of large vehicles such as trucks and buses is almost vertical. Please use optical knowledge to analyze the reasons for the installation of automobile front windshield.

14. In production and life, due to friction and other reasons, static electricity is often generated, which can be used and harmful.

(1) Please illustrate the advantages and disadvantages of static electricity in people's life and production.

(2) Please give examples to illustrate the specific measures to prevent the adverse effects of static electricity.

15. Shops often use scales to measure the quality of goods. When weighing, if a piece of mud sticks under the weighing pan, the weighing result is higher than the actual quality.

_ _ _ _ ("big" and "small"); If the weight is worn, the result of weighing is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

16. In our daily life, we often use "2 1 inch" and "29 inch" to describe the size of TV sets. Here, "inch" is the unit of length in what system? "2 1 inch" and "29 inch" refer to the length of which line segment on TV?

17. There is often a small hole in the lid of the pot for boiling water at home. If there is no hole, cover the lid tightly and what will happen if the water boils? Why?

18. The thermometer used by the weather station to measure temperature is installed in the shutters. What color is the shutter box? Why? What's the harm if you put it in a closed box? Why? What's the harm if you put it in the open air? Why?

19. The winnowing machine can separate grains, chaff and pebbles. Which of these three objects is closest to Yang Changji? Which is the farthest? Why do particles of the same size land at different distances from pebbles?

20. At present, the power supply system of new buildings no longer uses fuses, but uses automatic control safety circuits. When the electric load is too large or a short circuit occurs, the circuit will be automatically cut off; If a person standing on the ground touches the fire line, and the fire line and the earth pass through the human body, the circuit will be automatically cut off to ensure personal safety. Xiaoling has installed this kind of circuit in her new house. After moving, she saw that the power socket on the wall was three-wire. In order to install the TV, she bought a patch panel, plugged it into a three-wire socket on the wall, and then plugged the TV into the socket on the patch panel. But when the TV is turned on, all the sockets in the room are cut off, indicating that the circuit is automatically cut off. When I looked at the distribution box, it was indeed a "trip" (the main switch automatically cut off). Is there something wrong with the TV set, and it consumes too much power? Turn off the main switch by hand, and plug several other electrical appliances that can ensure normal operation into this plug board until the small desk lamp consumes only 15W, or so. However, plug the latch plate into other jacks on the wall, and everything is fine. What could be the problem? Why is this happening? How to solve it?

National junior middle school applied physics knowledge contest exercises (2) reference answers.

1 .b.2.c.3.b.4. Answer.

5. Answer: (1) Increase the heating area, (2) Enhance the mechanical strength.

6. A: 0.8 1,

7. Answer: 1 100, 1200.

8. Answer: (1) Change the magnitude or direction of the force with a lever; (2) The gas volume decreases and the pressure increases.

9. Answer: (1) Chemistry, machinery (or kinetic energy and potential energy). (2) C. (3) See if the genes of the seeds have changed under weightlessness.

10. A: The series heating is too concentrated, the local temperature is too high, and the insulation layer of the heating wire is burned, resulting in short circuit or leakage, and the thermal effect of the current.

1 1. A: Convert part of the kinetic energy of the car into gravitational potential energy to reduce the mechanical energy lost due to braking; When the car leaves the station, the stored gravitational potential energy is converted into kinetic energy, which plays an energy-saving role.

12. A: The density of seawater in different sea areas is different. The sea water density in the North Atlantic is higher than that in the Indian Ocean.

13. a: ensure the safety of driving at night. The front windshield of a car is installed obliquely, because the light from the vehicle behind shines on the front windshield and reflects obliquely downward; When the scene inside the car is illuminated, the image formed by the front windshield is located diagonally above the driver. In this way, the driver in the car will not be disturbed by the reflected light.

14. A: (1) Examples of using static electricity, such as people can use electrostatic dust removal, electrostatic copying and so on. Examples of electrostatic hazards, such as wearing chemical fiber clothes, are easy to "electrocute" or "vacuum".

(2) Specific measures to prevent the adverse effects of static electricity, such as dragging a chain at the tail of a car transporting gasoline to connect with the earth to prevent the accumulated electrostatic discharge from causing a fire.

15. A: Big, big and small.

16. Answer: "inch" is a British unit of length. "2 1 inch" and "29 inches" refer to the diagonal length of the TV screen.

17. Answer: If there is no hole in the lid and the lid is tight, water will be sprayed from the spout when boiling. This is because when boiling, the water vapor in the pot increases and the air pressure increases, and the water pressure in the pot will be released.

18. Answer. The blinds are white. If it is other colors, the temperature of the air inside the box will be obviously higher than the temperature of the gas outside the box when the sun shines, and the measured temperature is not the temperature of the air in the environment. If the thermometer is placed in a closed box, it will not measure the ambient temperature. This is because the air is not circulating and the temperature inside and outside the box is not equal. If the thermometer is placed outdoors, it can't measure the temperature either. This is because when the sun is shining directly, the temperature of the thermometer itself is not equal to the temperature of the surrounding air.

19. A: The landing point of chaff is closest to Yang Changji. The small stone is the farthest. Particles and pebbles of the same size have the same flight speed, but their kinetic energy is different because of their different masses. Small stones have greater mass and kinetic energy, which can overcome the resistance of air and fly farther.

20. A: The problem is that the zero line and the ground wire of the wall socket are connected in the wrong position during construction. When in use, the electrical appliance is used to connect the live wire and the ground wire, and the automatic control system mistakenly thinks that the human body is connected with the live wire and the ground wire, thus automatically cutting off the circuit. Corrective method: remove this socket from the wall and replace the position of zero line and ground line.