The total score of the topic is one two three four five.

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A, multiple-choice questions (3 questions each, score *** 18)

1. Xiaoming cooked the egg twice, and after the first cooking, he continued to cook it with high fire until it was cooked; After the second boiling, the flame was turned down, but the water in the pot kept boiling until it was cooked.

A. Compared with the second method, the first method saves fuel and time.

B. The first method consumes more fuel than the second method, but saves more time.

C. The second method saves fuel and time than the first method.

D. the second method is more fuel-efficient than the first method, and the two methods take about the same time. ( )

2. The following kinds of energy used for power generation do not come from outside the earth.

A. Wind power generation B. Thermal power generation

C. Atomic power generation D. Hydroelectric power generation ()

Imagine that from one day on, the gravity of the earth will be reduced by half, so for ships floating on the water, the following is true.

A. The gravity on the ship will be reduced, and the draft of the ship will remain unchanged.

B. the gravity on the ship will decrease, and the draft of the ship will also decrease.

C the gravity of the ship will not change, and the draft of the ship will not change.

D. the gravity on the ship will not change, and the draft of the ship will decrease. ()

4. When some metals or alloys reach a certain temperature, the resistance will become zero. This phenomenon is called superconductivity, and substances that can be superconducting are called superconductors. Please consider which of the following examples is not using superconductors.

A. transmission loss can be reduced.

B. it has developed into a maglev train.

C. Power generation equipment and motors with high assembly success rate and efficiency

D, manufacturing a high-power electric furnace ()

5. There is a disc resistor with a round hole drilled on it. As shown in the figure, four electrodes A, B, C and D are led out at 1/4 of the circumference. Comparing the sizes of resistors RAB and RCD, there are

A.RAB = RCD RAB

C.RAB。

( )

6. Xiaofang hangs a bar magnet with uniform mass distribution with fine iron wire in Beijing to keep its horizontal position balanced. The position of the messenger wire on the magnet should be

A. at the center of gravity of the magnet. On one pole of the magnet.

C. North side of the center of gravity of the magnet D. South side of the center of gravity of the magnet ()

Two. Fill in the blanks (***20 points)

1. When Yang Changji shipped the grain, it separated the second grain, stone and grass clippings from the finished grain. If Yang Changji is taken as the standard, the order of these four things from near to far is 1234.

There is a film with the word "F" written on the projector, which is for teaching. At this time, a clear image just formed on the screen. Please draw the image of "F" on the screen. If you want to get a bigger and clearer image, you should let the projector (fill in "away" or "near") screen and turn the lens.

(Fill in "Up" or "Down") Move.

3. Diodes are unidirectional devices, and the conduction direction is indicated by the middle arrow. If D 1 and D2 shown in the title are ideal diodes, the forward resistance is zero and the reverse resistance is infinite, ammeter A is an ammeter whose pointer can swing in both directions, and the resistance R1= R2 = R3 = 3Ω, the indirect voltage of A and B is constant under 9V DC power supply, when A is connected to the positive pole of power supply, A and B are indirectly connected to 9V power supply, and when B is connected to the positive pole of power supply, the pointer of ammeter.

4. As shown in the figure, there are four bricks with the same mass m between two identical vertical baffles A and B, and the baffles are all F with the same horizontal force to keep the bricks still, so the friction between the two bricks is 1, and the friction between the two bricks is 0.

5. Working and living in space, if you don't wear a spacesuit and only bring an oxygen bottle, can astronauts get out of the extravehicular activities? Give two reasons with what you have learned about physics. Answer: (Please fill in "Yes" or "No"). Because; .

Three. Answer the following questions briefly (4 points for each question, 16 points * * *).

1. Light pollution, like other pollution, will endanger human health, but the difference is that light pollution mainly harms human beings through vision. Due to people's neglect, the backwardness of technical means and the lack of protective measures, there is a tendency to flood.

Please give two examples of light pollution in life.

(2) Explain the possible harm caused by light pollution.

⑶ Put forward feasible suggestions to prevent light pollution.

Everyone who can ride a bike has this experience. On the flat ground, riding a bike is much more labor-saving than running. Why?

3. Why do fluorescent lamps save more energy than ordinary incandescent lamps?

4. The compression refrigerator uses the periodic state change of refrigerant in the refrigeration system to cycle refrigeration. The general structure of the refrigerator is shown in the figure. The upper layer is the quick-freezing room (cold source), and the lower layer is the refrigerating room, which is divided into three compartments: upper, middle and lower. Now there are a batch of fresh fish, meat, vegetables and fruits. How to scientifically store these foods in the refrigerator grid? Why is this the best way to keep fresh?

Iv. Experimental questions (1 question 4 points, 2 questions 8 points, 3 questions 6 points *** 18 points)

1. Observation and experiment are the basis of physics. Please give two examples of obtaining electrical knowledge through observation and experiment. (Requirements: Write down the purpose, process, phenomenon and conclusion of the experiment)

Example: experimental purpose: is there a magnetic field around the charged conductor?

Process and phenomenon: when the small magnetic needle is placed near the charged conductor, the small magnetic needle deflects.

Conclusion: There is a magnetic field around the charged conductor.

A: (1)

⑵

2. There is a constant resistor R0 with a resistance of 40Ω, a power supply with a voltage of about 35V, an ammeter with a range of only 0-0.6A, and a sliding rheostat with a maximum resistance of about100Ω. Please design an experiment to accurately measure the resistance of a resistor RX with a resistance of about 55 Ω. ask

Draw a circuit diagram

⑵ Write down the experimental steps and indicate which quantities need to be measured.

⑶ Derive the mathematical expression of the resistance to be measured from the measured value (note: the circuit can be repeatedly connected).

3. Xiaogang can use a platform scale, a piece of paper and a basin of water to roughly measure the ground force of volleyball when it lands. Can you tell how he did it?

Verb (abbreviation of verb) calculation problem (1 question 12, 2 questions 16 * * 28)

1. There are six identical cups, one of which is filled with hot water. If you want to use the heat absorption of the cup to reduce the temperature of hot water, you can inject hot water into the other five cold cups to let the cups absorb the heat of hot water. How to inject hot water to get the best cooling effect?

[Method 1] Hot water is injected into five cups on average, and each cup is equipped with 1/5 hot water.

[Method 2] First pour the whole cup of hot water into the second cup, then pour the whole cup into the third cup when the cup no longer absorbs heat, and so on, and finally pour into the sixth cup.

Which method do you choose? Write down the reasons for your choice.

(2) If the mass of hot water is 100g, the temperature is 90℃, the mass of glass is 50g, the temperature is 10℃, and the specific heat capacity of glass is 0.84× 103J/(㎏. C), please calculate the lowest temperature that can reduce hot water?

2.( 16 minutes) Figure (a) is a schematic diagram of salvaging underwater heavy objects by car. The trolley drags an underwater cylindrical weight through the crown block. During the whole fishing process, the trolley moves to the right at a constant speed of V = 0.2m/s. Figure (b) shows the change of the power p of the trolley pulling the weight with time t, let t=0, and ignore the gravity of water and the friction of pulley. Let g be 10N/ and find:

(1) The mass of the cylindrical weight?

(2) What is the density of the cylindrical weight?

(3) What is the water pressure on the upper surface of the cylindrical weight before fishing?

(4) How much work did Che * * * do for the heavy objects from the moment when the cylindrical heavy objects just surfaced?

References:

/editor/UploadFile/2005- 12/ 12/2005 12 12829 1569 . doc