A. the gravitational potential energy is decreasing. B. the kinetic energy is increasing.
C. kinetic energy first decreases and then increases. D. the gravitational potential energy first decreases and then increases.
2. In daily life, in order to let students form the good habit of paying attention to life and society, physics teachers advocate students to estimate some common physical quantities around them. The following are some estimated data when they communicate. What do you think is that the data is obviously not realistic?
A.the gravity on the pencil is about 5N.
B. The normal walking distance for adults is about 400 meters.
C. Generally, the temperature of bath water is around 38℃.
D. the length of the blackboard is about 4 meters.
3. A Jing Wong family went on a May Day trip and saw a toothpaste for travel in the hotel (as shown in figure 1). According to your observation and life experience, you think the following statement is wrong.
A. When squeezing toothpaste, it can be reflected that the output can deform the object.
B. The stripes on the toothpaste cover are to increase friction.
C. the gravity of the whole new toothpaste is 0.03N n.
D. The sharp object in the middle of the toothpaste cover is to increase the pressure.
4. As shown in Figure 2, regarding the scene of the 60th National Day military parade, the following statement is correct.
The red flag fluttering in the wind is red because it refracts red light.
B the whole queue is uniform, and the audience judges it by the light traveling in a straight line.
The military emblem on a soldier's hat glows because it is a light source.
D the soldiers' loud slogans were introduced to the surrounding audience through electromagnetic waves.
5. As shown in Figure 3, in order to make the lever in a balanced state, among the four forces acting on point A respectively,
A.f 1 B . F2 C . F3 D F4
6. When Xiao Qiang looks at a certain point in the distance, his optical path is as shown in Figure 4, so the following statement is correct.
Xiao Qiang's eyes are short-sighted. He should wear glasses made of convex lenses.
Xiao Qiang's eyes are nearsighted, so a concave lens should be used.
Xiao Qiang's eyes are farsighted. He should wear glasses made of convex lenses.
D Xiao Qiang's eyes are normal. He doesn't need to wear glasses.
7. At present, the voice of manufacturing China's own aircraft carrier is getting louder and louder. As shown in Figure 5, a picture of a Chinese aircraft carrier provided by a netizen. After the carrier aircraft of the aircraft carrier flies away from the aircraft carrier, there are
A. the aircraft carrier will float and the buoyancy will decrease.
B. The aircraft carrier will sink and its buoyancy will increase.
C. the aircraft carrier will sink and the buoyancy will decrease.
D. the aircraft carrier is always floating, and its buoyancy remains unchanged.
8. A father and his 5-year-old son Lei Lei went upstairs to go home. In this regard, the following statement is wrong.
A. Climbing the same stairs, my son does less work because of his small weight.
B. Climbing the same stairs, my father's weight makes him do more work.
C. Climbing the same stairs, the son arrives before his father, which must be very powerful.
D. Climbing the same stairs, the father arrives before the son, and the father must have great power.
9. As shown in Figure 6, the bar magnet is suspended directly above the electromagnet by a spring. When the switch is closed and the slider P slides from the A end to the B end, the following phenomena will occur.
A. The current representation becomes smaller and the spring length becomes shorter.
B. The current indication number becomes smaller and the spring length becomes longer.
C the larger the current representation, the longer the spring length.
D. The current indicator becomes larger and the spring length becomes shorter.
10. The car is equipped with an indicator light to remind the driver whether the door is closed. As long as one of the four doors is not closed (equivalent to a switch being closed), the indicator light will light up to remind them. In the four circuits shown in fig. 7, the working principle of the device can be embodied as follows.
1 1. Connect the A lamp marked "36V 15W" and the B lamp marked "36WW" in series and connect them in a circuit with a voltage of 36V.
A. Because the greater the rated power of a lamp, the brighter it will be.
B. Because the currents passing through them are equal, they are equally bright.
C. because the resistance of the lamp is small, the lamp is on.
D. Because the actual power of lamp B is greater, lamp B is brighter.
12.4 1 The World Expo opened in Shanghai on May 10. In order to embody the theme spirit of "Better City, Better Life", some students in a school put forward the following environmental protection suggestions, among which you think it is feasible.
① Develop new energy sources and reduce the burning of fossil fuels; ② Advocating the use of disposable foamed plastic tableware and plastic bags; ③ Develop and produce mercury-free batteries; ④ Advocating the use of handkerchiefs and reducing the use of napkins; ⑤ Garbage classification and recycling.
A.①③⑤ B.①③④⑤ C.①②③⑤ D.①②③④⑤
2. Fill in the blanks (this big question contains 6 small questions, each small question 1 point, * * *1point)
1. As shown in Figure 8, it is the China Pavilion, the core building of the 20 10 Shanghai World Expo. Its super-large foundation makes the main building fall to the ground by increasing the stress area. In the museum, the audience can take a rail car for sightseeing. If the rail car travels 900m in 6 minutes, the average speed of the rail car is m/s.
2.2065438+On March 28th, 2000, a flooding accident occurred in Wangjialing Coal Mine, and the rescue work started rapidly. On the afternoon of April 2, the accident mine issued signs of existing life. It turned out that the trapped people issued a "Dangdang" distress signal by tapping the drill pipe. This is because the sound transmission effect is better than gas.
From 3.201110, smoking will be completely banned in all indoor workplaces, public transport and other possible outdoor workplaces in China. In the moving carriage, a passenger smokes, making the whole carriage smoky, which belongs to the phenomenon of _ _ _ _ _ _ _ _ _; Xiao Ming and other passengers became passive smokers, so Xiao Ming opened the window and saw white smoke outside the car. This is because the velocity of outside air is greater than that of inside air, which makes the outside air pressure _ _ _ _ _ _ _ (please fill in "greater than", "less than" or "equal to").
Zhang Lei found that the electric fan at home often has some dust on its blades after being used for a period of time. One of the reasons is that the blades are easy to absorb dust.
5. As shown in Figure 9, the oil storage tanks in Snoely are silvery white and stocky. Then:
(1) The oil storage tank is "completely silvery white" because light color can absorb sunlight better than dark color.
(2) An automatic spraying device is installed beside the oil storage tank. Every summer at noon, the sprinkler will spray water on the oil storage tank, mainly because the water absorbs heat, which can cool the oil storage tank and prevent the oil from spontaneous combustion. On June 20th1September18th, Dezhou will hold the 4th World Sun City Conference to make every effort to build a "green capital". As shown in figure 10, Dezhou is a street lamp for the renovation of Sun City Conference. At the top of the lamppost is a solar panel, which can convert solar energy into electric energy and charge the storage battery under the lamppost for street lighting at night. If, in a certain period of time, the energy radiated by sunlight to the solar panel is 2. 1× 107J, which is the same as the heat released by completely burning _ _ _ kg coal (equivalent to the calorific value of coal of 3.0×107j/kg); After energy conversion, a 30W street lamp can work for 70h, so the energy conversion efficiency of solar street lamp is _ _.
Three, drawing, experiment, inquiry questions (this big question contains 7 small questions, ***24 points)
7.(2 points) Please read the indicators of each measuring tool shown in the figure below and fill them in the horizontal line below: the length of the wood block is cm; The gravity of an object is _ _ _ _ _ _ n.
8.(2 points) Please connect the lights, switches and sockets in Figure 13 to the household circuit with wires instead of wires.
9.(2 points) As shown in figure 14, the light lever can rotate around O, and a heavy weight G is hung on the lever. Under the action of force F, the lever is in a horizontal position, and L is the arm of force F. Please make a schematic diagram of the force F and the weight G in the figure.
10.(5 points) Anna wants to use the experimental equipment given in Figure 15 to "measure the rated power of small light bulbs". Known power supply voltage is 6V, rated voltage of small bulb is 3.8V, and resistance is about10Ω.
There is an obvious error in the circuit connection of (1). Please mark the mistakes with "X" and draw the correct circuit connections in the original drawing.
(2) After the circuit is correctly connected, when the switch is closed and the slider P moves to a certain point, the voltage representation number is 2.4V；; Continue to move the slider P to the (optional "A" or "B") end. At this time, the voltmeter indicates 3.8V, the ammeter indicates A, as shown in figure 16, and the rated power of the small bulb is W. 。
1 1.(4 points) Through the study of physical knowledge, students can easily find:
(1) When it is difficult to measure the physical quantity to be studied directly, it should be expressed indirectly as far as possible. For example, in the experiment to explore which factors are related to friction (as shown in figure 17), when pulling a wooden block with a spring dynamometer, the wooden block must move on a horizontal plane, and the friction can be indirectly known by reading the indicator on the spring dynamometer; For another example, in the experiment of studying Newton's first law (as shown in figure 18), let the same car roll down from the same height on an inclined plane and move on planes with different roughness, and the force on the car in the horizontal direction can be expressed by the car. (2) This method is generally used when studying the relationship between a physical quantity and multiple factors. For example, in the experiment to explore the relationship between friction and pressure, it is necessary to change the roughness of the contact surface many times while keeping it unchanged.
12.(3 points) Xiaohua wants to measure the density of a stone with a balance and a measuring cup.
(1) When adjusting the balance line, it is found that the index dial pointer is as shown in figure 19. At this time, the balance nut should be adjusted to the (optional "left" or "right") end.
(2) Measure the quality of the stone with the adjusted balance. If the balance is balanced, the mass of the right plate weight and the position of the line code on the scale are as shown in Figure 20, then the mass of the stone is g; If the volume of the stone measured by the measuring cup is 15.8cm3, the density of the stone is g/cm3.
13.(6 points) In junior high school physics experiments, many problems can be studied by using cuboid wood as experimental equipment. Now please use cuboid wood as one of the experimental equipment, and you can add other auxiliary equipment appropriately to design two experiments to study or explain related physical problems. (Force, heat, sound, light and electricity are all acceptable)
Add major equipment
Main experimental process
Learn or explain.
Physical problems
example
Spring dynamometer,
microgroove
Hang the wood block on the hook of the spring dynamometer with thin thread, and read the reading of the spring dynamometer when the wood block is stationary.
The block of wood is subjected to gravity.
Design 1
Design 2
Fourth, the calculation problem (this big problem contains 2 small questions, *** 12 points. When answering, you should write the necessary text descriptions, formulas and important calculus steps, and only write the final answer.
14. electric bicycles have become an indispensable means of transportation in our lives (as shown in figure 2 1). When electric riding, the battery supplies power to the motor on the car and provides power for the car. The following table is the main technical parameters of an electric bicycle. Q: The vehicle mass is 35kg.
The maximum speed is 30 km/h.
The tire pressure limit is 2× 105Pa.
The maximum noise is 62dB.
Battery 36V/ 10Ah
The rated power of the motor is 36V.
The efficiency of a motor rated at 240W is 80%.
(1) What is the working current of the electric bicycle at rated power?
(2) The contact area between each tire and the ground during driving is 0.005m2 A middle school student rides an electric bicycle on a straight road. Try to calculate the pressure on the ground. (g is 10N/kg, and the weight of middle school students is 50 kg).
15. As shown in Figure 22, rope weight and friction are not included. The stevedores hoisted the cargo weighing 800N to a high place, and the pulling force of people on the rope F 1 was 50.
(1) Request the mechanical efficiency of the pulley block in (2);
(3) If the weight is 600N, lift the weight for 5m and find the work done by the pulling force.