20 15 8th grade physics final exam questions and answers last semester.
The first volume (multiple choice questions, ***24 points)
First, multiple-choice questions (2 points for each small question, 24 points for * * *, and only one option for each question meets the meaning of the question)
1. As shown in the figure, there are 3m Takaso transparent walls on both sides of the urban elevated section. The main purpose of installing these walls is ().
A. protect the driving safety of vehicles
B. Reduce vehicle noise pollution
C. Increase the aesthetic feeling of the elevated road
D. stop the leakage of vehicle exhaust gas
2. In the following description of the beautiful scenery of the four seasons, only the liquefaction phenomenon is ().
A. in spring, it rains all over the mountain. In summer, fog hangs over the peaks.
C. In autumn, frost hits the branches. D. in winter, the bottom freezes.
3. "Yuba" is a common equipment in family shower room. Regarding "Yuba", the following statement is true ().
A equipped with infrared light bulbs, mainly used for lighting and sterilization.
B equipped with ultraviolet light bulbs, mainly used for lighting and disinfection.
C equipped with infrared light bulbs, mainly used for heating and lighting.
D equipped with ultraviolet light bulbs, mainly used for heating and lighting.
4. Around the Spring Festival in 2008, parts of southern China suffered from low temperature, rain and snow. In the description of the following related figures, the incorrect one is ().
A. In Figure (a), rime is a condensation phenomenon of water vapor and an exothermic process.
B in figure (b), traffic control is needed because the light reflected by the ice surface is too strong.
C in figure (c), spraying salt on the ice surface of expressway is to melt the ice by lowering the melting point.
D. The ice hanging on the bamboo in Figure (d) is solidified by rain, which is an exothermic process.
5. There is an electric toothbrush, which sends out ultrasonic waves to places that the toothbrush can't reach, a brown brush, so that brushing your teeth is clean and comfortable. About electric toothbrush, the following statement is correct ().
A. When brushing teeth, people can't hear ultrasonic waves, because ultrasonic waves can't spread in the air.
B.the tone of ultrasonic wave is so low that people can't hear it.
C. ultrasonic waves are not generated by the vibration of objects.
D. Ultrasonic energy can transmit energy.
6. Among the four images of Fuwa in the box below, one is the image of Fuwa in the vertical plane mirror, which should be ().
7. The safety light for processing black-and-white photos in darkroom is red, and the thermometer column used is blue instead of red. Regarding the liquid column of this thermometer, the following statement is correct ().
The blue liquid column of the thermometer looks white under red light.
The blue liquid column of the thermometer looks black under red light.
The blue liquid column of the thermometer looks red under red light.
The blue liquid column of the thermometer looks magenta under red light.
During the torch relay of the 2008 Beijing Olympic Games, a reporter photographed the national flag fixed on the ground and the nearby Torch A and Torch B, as shown in the figure. According to the flag and flame fluttering direction, you can judge ().
A. welding torch a can move to the right, while welding torch b can stand still.
B. welding torch a must move to the right and welding torch b must move to the left.
Torch A can be moved to the right, but torch B must be moved to the left.
Welding torch A must move to the right, while welding torch B can move to the left.
9. About the solar eclipse, the following statement is correct ().
A. It's all caused by the straight-line propagation of light. An eclipse is when the moon blocks the sunlight.
B: It's all caused by the reflection of light. During the eclipse, the moon blocked the sunlight.
C. It's all caused by the straight-line propagation of light, and the solar eclipse is that the earth blocks the sunlight.
D. It's all caused by the straight-line propagation of light. An eclipse is when the moon blocks the sunlight.
10. As the picture shows, Xiao Ming made a simple projector. In the darkroom, he pasted the transparent film printed with the five Olympic rings (red, yellow, blue, green and black) on the white flashlight, pointed it at the convex lens with the focal length of 10cm, and adjusted the position between the flashlight, the convex lens and the white wall to get a clear picture on the wall.
A The distance between the flashlight and the convex lens should be less than 10cm, and the film should be placed vertically.
B the distance between the flashlight and the convex lens should be greater than 10cm and less than 20cm, and the film should be inverted.
C the image of the five-ring sign on the wall can be seen from different angles, because the light is diffuse on the wall.
D Cover the white wall with a layer of red cloth. You can see that the colors of the five rings in the image are only red and black.
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12. The plane mirror coated with semi-permeable membrane can transmit and reflect the projected light. At present, a film crew is shooting at the seaside. When the lens is aimed at the sea, a semi-transparent plane mirror MN is placed between the lens and the sea at an angle of 45, with running actors and cars on both sides of the mirror, as shown in the figure. When showing the film, the screen ().
A.only actors run on the sea.
B.only cars travel on the sea.
C. Actors run on the beach and cars run on the sea.
D. Actors run on the sea and cars run on the sea.
Volume 2 (multiple choice questions, ***76 points)
Fill in the blanks (this topic is ***9 small questions, 1 point per space, ***24 points)
13. The "high" in the poem "dare not speak loudly for fear of disturbing people" refers to _ _ _ _ _ _ loud voice; Zhai Zhigang and two astronauts, Liu Boming and Jing Haipeng, cannot talk directly in space because of _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _; A big horn can make the candle flame in front of it "dance", indicating that there are _ _ _ _ _ _ _ _ _ _ _; When listening to different instruments playing the same song, you can distinguish the instruments used, which makes use of the _ _ _ _ _ _ difference in sound.
14. Both cars A and B are moving in a straight line at a constant speed. It is known that the speed ratio of A and B is 3: 1 and the passing distance ratio is 2: 1, then the time ratio of A and B is.
15. The measuring range of the thermometer is℃, and the pointer of the thermometer in Figure A is℃. The mercury column is thin and difficult to read, so the thermometer is made into a convex curved glass surface with a cross section as shown in Figure B. If the position of the liquid column in the thermometer can be clearly seen, observe along the direction (choose "A", "B" or "C"). This is the use of.
16. As shown in the figure, it is the temperature-time image when A and B are melted, in which _ _ _ _ _ _ _ _ _ is amorphous. The melting point of the crystal is _ _ _ _ _ _ _℃
17. As shown in the figure, it is the longest sea-crossing bridge in the world-Hangzhou Bay Sea-crossing Bridge, with a total length of 36 kilometers. The bridge was opened to traffic on May 1 2008. After opening to traffic, the land distance from Shanghai to Ningbo is shortened by about 120km. If the car travels at a constant speed of 100km/h, the travel time from Shanghai to Ningbo will be shortened. Taking the bridge railing as the reference object, the driver is correct (choose "static" or "moving"); Cars driving at a constant speed on a horizontal bridge deck have the ability; The reflection of the bridge in the water is an image (choose convex lens or flat mirror).
18. As shown in the figure, it is a stroboscopic photo of a ball moving in a straight line from point A to point F. The camera flashes every 0. 1. According to the photo analysis, the ball moves in a straight line from point A to point F (choose "constant speed" or "variable speed"); The average speed of the ball moving from point D to point F is _ _ _ _ _ _ m/s. 。
19. Fill in the blanks: (1) As shown in the figure, two identical electric kettles have the same water capacity and are heated by the same heater. At this time, the water has been boiled, so the temperature of room A (please select "high", "low" and "etc.") is the temperature of room B; (2) As shown in the figure, when C and D look at objects, they show the optical path diagram of their eyes. In order to form a clear image on the retina, C needs to wear glasses with mirrors.
20. Face recognition system was adopted in the security work of Beijing Olympic Games. As shown in the figure, the camera of the recognition system can automatically take a digital photo of the face at 1m in front of the camera and transmit it to the computer for recognition. The lens of the camera in this system is equivalent to a _ _ _ _ _ _ lens, and the focal length is less than _ _ _ _ _ _ _ cm.
2 1. As shown in the figure, a plane mirror is placed in the center of the cylinder, opposite to a point light source S on the wall of the cylinder, and the point light source emits a thin beam vertically to the plane mirror. The plane mirror rotates at a uniform speed around the central axis o of the cylinder from the position shown in the figure. When the rotation angle is 30, the angle of the reflected light spot irradiated on the cylinder wall is, and the angle of the connecting line between the image point and the point light source S is.
Three, drawing and experiment problems (this problem ***7 small questions, ***28 points)
22.(4 points) Connect the following physical phenomena with the matching conjecture with short lines.
Speculation of physical phenomena
When beating the drumhead, the melting point of the beating crystal of the small pieces of paper on the drumhead is related to the mixed impurities.
Sprinkle salt on the icy road to melt the ice. Tone is related to vibration frequency.
Planes will have dangerous reflections when they meet birds.
Driving at night and turning on the lights in the car are relative.
23.(3 points) As shown in the figure, after sunlight passes through the prism, a colored light band will be formed on the light screen. This phenomenon is called _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. In _ _ _ _ _ _ Figure, the _ _ _ _ _ _ surface of the light screen irradiated by the light beam has obvious thermal effect (select "top" or "bottom").
24.(7 points) As shown in Figure A, the experimental device diagram of "Exploring the imaging law of convex lens". During the experiment, the focal length f of the convex lens is measured by sunlight. Please seriously consider the following four experimental design schemes and answer the questions.
A: Place the lighted candle at the focal length f and the focal length 2f respectively, adjust the distance between the screen and the convex lens, observe and record whether it can be imaged on the screen and the imaging characteristics, and get the law of convex lens imaging.
B: In addition to the method in A, put the candle at a position greater than 2f and a position greater than f but less than 2f, observe and record the corresponding imaging situation, and get the imaging rule of convex lens.
C: In addition to the method in A, the lighted candle gradually moves closer to the convex lens from a distance. By constantly adjusting the distance between the light screen and the convex lens, we can observe and record whether the image can be imaged on the screen and its characteristics, including observing the changing trend of the formed image with the position of the candle, and get the law of convex lens imaging.
D: Different from C, the candle gradually moves away from the convex lens, and the other steps are the same.
(1) Among the above four schemes, the reasonable scheme is _ _ _ _ _ _ (choose "A", "B", "C" and "D");
(2) A set of images that record and draw the relationship between the distance u from the object to the convex lens and the distance v from the image to the convex lens, as shown in Figure B. From the image point of view, when u= 15cm, a _ _ _ _ _ _ _ _ image can be obtained on the screen; In the process of moving the object from 10cm to 30cm away from the convex lens, The change of image size is _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
A group made an experiment with two lighted candles. Put the candle, the convex lens and the light screen in the position shown in Figure C, and the connecting line AB of the two candles is perpendicular to the center line of the convex lens, then the imaging size of C and D on the light screen is _ _ _ _ _ _ _ _ _ _ (fill in "equal" or "unequal"); Block the candle flame at A with a piece of cardboard, and you can still get a clear image at _ _ _ _ _ _ _ _ _ (choose "C" or "D") on the screen.
25.(6 points) In the experiment of "observing the boiling of water":
(1) In addition to the instruments provided in the experimental device diagram, instruments are needed.
(2) The experiment is mainly to observe and compare the water before boiling and when boiling.
And the change of bubbles in water.
(3) If the alcohol lamp is removed in the process of water boiling, the boiling phenomenon will stop (choose "Yes" or "No"), indicating _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.
(4) When the water boils, the bubbles formed gradually change when rising from the bottom of the cup (choose "big" or "small").
26.(3 points) As shown in the figure, the light enters the air obliquely from the glass, and MN is the interface. Mark the propagation direction and refraction angle α of light with arrows.
27.(2 points) As shown in the figure, please refract the incident light through the lens.
28.(3 points) As shown in the figure, it is the schematic diagram of the laser liquid level controller. A beam of fine laser AO emitted by the fixed laser is aimed at the liquid surface at an incident angle of 60 degrees, and then reflected by the liquid surface and directed at point B on the vertical light screen, and then the optical signal is converted into an electrical signal by the photoelectric converter on the light screen, which is input into the control system to control the height of the liquid surface. Please draw a picture to find the exact location of point B. When the liquid level rises by H height, the light spot B on the light screen rises by _ _.
4. Answer (this question is ***4 small questions, with ***24 points, and the answer should have the necessary text description, formula and calculation process)
29.(4 points) As shown in the figure, press one end of the ruler tightly on the desktop, and you will hear the sound when you move one end out of the desktop. What can this device explore about acoustics? (Write two points)
30.(3 points) In summer, Xiao Ming took out some ice cubes from the freezer of the refrigerator and put them in a cup filled with normal-temperature mineral water. After a while, he stirred the ice cubes with a straw and found that the ice cubes "stuck" together, as shown in the figure. Please explain this phenomenon.
3 1.(5 points) A car starts from Station A, travels 300m in the first 20 seconds, then travels at a constant speed of 36km/h for 2min, and finally travels 300m at 1min to bilibili. Find: (1) the average speed of the car in the first 20 seconds; (2) The distance between Station A and bilibili; (3) The average speed of the car in the whole process.
32.(5 points) As shown in the figure, two equal plane mirrors A and B stand upright on the ground with a height of 0.95m and a distance of 20cm. There is a thin laser beam at an angle of 45 degrees to the vertical. The angle hits the upper edge of the plane mirror B, and hits the ground after many reflections. Find:
(1) How many times did a * * * reflect when the laser beam hit the ground?
(2) The distance between the spot projected on the ground and the A-mirror.
33.(7 points) Party A, Party B and Party C start from the same place at the same time and move in a straight line in the same direction. Party A and Party B move in a straight line at a uniform speed, while Party C accelerates from standstill. The speed-time image is shown in the figure. Find:
How far is A from B after (1) 10?
(2) When the speeds of C and A are equal, how far does A move?
(3) How long will it take C to catch up with B? How fast is C moving at this time? (Hint: the average speed of C is equal to half of the sum of the initial speed and the speed when catching up with B)
First, multiple-choice questions (2 points for each small question, ***24 points)
The title is123455678911112.
Answer B B C B D A B C A A D C
II. Fill in the blanks (65438+ 0 for each blank, ***24)
13. Loudness (volume) cannot transfer energy in vacuum. Tone14.2: 315.35 ~ 42 38.2b Principle of positive magnification of virtual image by convex lens 16. B 80 liquid 17. 1.2 moving flat mirror.
18. Speed change is 0.4 19. Smaller than concave surface 20. Convex 50 2 1.60 30.
Three, drawing and experiment questions (***28 points)
22.(4 points) Connect the following conjectural phenomena with short lines.
Speculation of physical phenomena
When tapping the drumhead, the melting point of the tapping crystal of the small pieces of paper on the drumhead is related to the impurities involved.
Sprinkle salt on the icy road to melt the ice. Tone is related to vibration frequency.
Planes will have dangerous reflections when they meet birds.
Driving at night, it is not easy to turn on the light in the car, which is relative.
23.(3 points) Dispersion refraction
24.(7 points) (1) C, D (2 points) (2 points) The upside-down stereo (also points should be given) becomes smaller and smaller (3 points are equal) C 25. (6 points) (1) Stopwatch (2 points) Temperature of water (3 points) Sound made when water is boiling.
26, 27. As shown in the figure (***5 points)
28. Figure (2 points) 2h( 1 min)
Note: Question 26 ***3 points, the propagation direction of incident light and refracted light is 1 minute, and the angle is 1 minute, so it is impossible to deduct 1 minute (both normal and virtual); 27 questions ***2 points, two rays each 1 minute, one arrow less 1 minute; The 28 questions are plotted as 2 points, and the normal and reflected light are each 1 minute (the normal can be true or false, and there is no arrow deduction 1 minute). If the symmetry method is used for drawing, the image point and the reflected light are 1 point respectively.
Four, answer questions (***24 points)
29.(4 points) (1)① Sound is caused by the vibration of objects;
(2) Significantly change the length of the scale protruding from the desktop, and with the same strength as last time, the tone of the sound can be heard changed;
(3) The length of the scale protruding from the desktop is certain, and it can be heard that the loudness of the sound has changed with the intensity.
30.(3 points) When the temperature of the ice cubes taken out of the freezer is lower than 0℃, the water releases heat to cool down and the ice absorbs heat to raise the temperature (1 min); When the water temperature near the ice drops to 0℃, the temperature of the ice is still below 0℃ (1); The ice cubes continue to absorb heat, and the water at 0℃ near the ice cubes continues to give off heat and solidify into ice, so the ice cubes will stick together (1 min).
3 1.(5 points) Solution: (1) The average speed in the first 20 seconds is
v 1 = S 1/T 1( 1)
= 300m/20s = 1 5m/sec (1point)
(2) the middle speed v2 = 36km/h =10m/s.
The middle distance is S2 = v2t2 =10m/s×120s =1200m (1min).
The total distance is s = s1+S2+S3 = 300m+1200m+300m =1800m (1min).
(3) The total time is total = t1+t2+t3 = 20s+120s+60s = 200s.
The total average speed is vtotal = stotal/ttotal =1800m/200s = 9m/s (1min).
32.(5 points) Solution: (1) Because the incident angle is also 45? , so every reflection, the light drops by 20cm (1 min).
The number of reflections is n=95cm/20cm=4.75 (1).
So the number of reflections should be 5 (1 min).
(2) The height of the fifth reflection point from the ground is
h/= 95cm-20cm×(5- 1)= 15cm。 ( 1)
Therefore, the falling point of light is 5cm( 1 min) from mirror B and 5 cm (1min) from mirror A..
33.(7 points) Solution: (1) The distance between Party A and Party B is
S 1=v A t-v B t ( 1)
=10m/s×10s-5m/s×10s = 50m (1point)
(2) When the speeds of C and A are equal, A moves for 20s, so the distance that A moves is
S A =v A t (1 point)
=10m/s× 20s = 200m (1point)
(3) Let the speed when C catches up with B be V, and the required time be T, then
T= v B t (1 point)
V=2v B = 10 m/s (1 point)
According to the picture, it takes 20s for C to catch up with B (1min).