2009-20 10 First semester, mid-term quality research.

Physics problems in ninth grade

2009. 1 1

A multiple-choice question (the test paper is full of two points and ***36 points. Of the four options given in each question, only one is correct. Please fill in the correct options before the brackets after the question. )

1。 Just like the daily necessities in the picture, they use a laborious lever ()

2。 Hercules competition, a project with wheels going up stairs. The following is the method of turning the wheel to step 4, and the function of the thrust in the same thrust direction, as shown in the figure, in which the most labor-saving method is pushing (using).

3。 As shown in four examples, the mode of action changes the internal energy ().

① Rub the wok in winter ④ Steam cork red.

When your hands are warm in winter, turn on the gas to heat the hot water, and the temperature will drop.

A.①②B.②③C.③④D.①④

AB crane lifts a horse-drawn car, and the car jumps D.

C. The diver jumps off the weightlifter and lifts the barbell.

5。 The same object moves at a uniform speed along the same horizontal ground, as shown in the figure below. The pulling forces FA, FB and FC between the pulley and the light rope can't remember the friction force between them, so they are larger ().

Auto focus: FB & gtFC CF A & gtFB = FC DF A =? FB> football club

6。 Temperature, heat, internal energy, the following statement is correct ()

A the higher the temperature of an object, the ice containing heat at B.0℃ will have no internal energy.

C when an object absorbs heat, its temperature does not necessarily rise. When it acts on an object, its temperature will rise.

7。 Shenzhou VII manned spacecraft completed various tasks. During the return process, the return capsule enters the atmosphere and passes through the black barrier for a period of time. The spaceship fired a big fireball. At this time shown in the picture, the astronaut spacecraft and its equipment are safe and harmless. The following statement is correct ().

A the "burning" of the spacecraft is because the friction energy between the spacecraft moving at high speed and the atmosphere is mechanical energy/>; B The "burning" of the spacecraft is due to the friction between the spacecraft flying at high speed and the atmosphere.

C. The astronauts of the "burning spaceship" took high-temperature disinfection measures to eliminate bacteria in space.

D, the ablation layer on the spacecraft shell melts and vaporizes for the first time, releasing a large number of heat-resistant spacecraft.

8. As shown in the figure, the rod is in a horizontal position in a balanced state, which is even and equidistant from the lever of each cell, and each hook code is the same. In the next four operations, the right end of the declination () will be used.

(1) Tick the code at the same time, and make full use of the outward movement of small units on both sides.

(2) Make full use of the hook codes on both sides and move one small square inward at the same time.

③ Make full use of the hook codes lost by both parties at the same time.

(4) Make full use of the hook codes of both parties and add hook codes respectively.

A.①③B.②③C.②④D.①④

9。 The picture shows the schematic diagram of four students completing the knowledge of circuit connection. You should be able to ensure that the correct circuit switch S is closed and that two small light bulbs are lit ().

10。 At present, most agriculture in China has been mechanized. It's slower to use tractor roots than on the road, ()

A. Improve the efficiency of transmission machinery and the power of diesel engine.

C. save fuel. D. 1 1 tractor traction. In the activities of the school's autumn track and field sports meeting in 2009, the ninth grade boys collectively pulled up, as shown in the figure. Roughly estimate the strength of the students' pull-ups. The following physical quantities do not need to be measured ()

A. Xiaoming's quality B. The height of the horizontal bar

C. The height of each body rises D. Jinning period

12。 The lift of elevator B is more efficient than that of elevator B, and the objects have the same uniform mass, thus increasing the same height. Compared with elevator a ()

A. the total work is completed by motor B. total work

C. heavy lifting motors do useful work.

13 The following error ()

A. heat engine, the so-called b heat engine. A large number of heat engines may cause environmental pollution.

B. The exhaust gas of the heat engine takes away a lot of heat D. Through technical improvement, the efficiency of the heat engine can reach 100%.

14。 It shows that the weight of the moving pulley used by workers in 10 second is 100 N (including the bucket) and it is even 5m upward in the vertical direction. If the moving pulley is-10N, the friction between the rope and the pulley is ignored, and the air resistance is not included. The following statement is correct ().

A. the strength of the rope pulling f 500 j during the lifting process.

B. the reaction force of rope tension f during lifting.

550 am. In the process of popularization, the acting power of rope tension F is 50 watts.

The mechanical efficiency of the pulley device of D is a matter of 100% experiment times.

Tension F/N

1 1.0 0.65

2 1.5 0.90

3 2.0 1. 15

15 students studied the characteristics of moving pulley in the experiment and recorded the following data table. After data analysis, it is found that the experimental results are inconsistent with the conclusion that the movable pulley in the textbook can save half of the electricity. After facing the facts, in the most dissatisfied way ()

A. if the experiment fails, stop the experiment.

B. analyze the possible reasons with your classmates.

C. retest under improved experimental conditions.

D. obtain information and understand the applicable conditions of the conclusion.

16. At 0: 0016 on April 5, 2009, the second Beidou navigation satellite was successfully launched into the scheduled orbit by the Long March III C carrier rocket in xichang satellite launch center. "cz-3 uses liquid hydrogen as rocket fuel, liquid hydrogen ().

A. The specific heat value is higher than the heat capacity BCD with lower boiling point, and the freezing point is higher.

17。 As shown in the figure, an inextensible string has one end fixed to the O point, the other end is a ball, the O point is fixed, and there is a nail P under it. Position 1, position 3 and the point are directly below the contour line o, the fifth position is a point between a and l, the second position is a point between 1 and 3, and the fourth position is a point greater than 3. Regardless of air resistance, the ball is released from the rest point ()

A: First of all, position L reaches the highest position 2 b. The position L that was surpassed for the first time reaches the highest position 4.

C. the second passing position is 1, and the highest reaching position is 5 d. the closing position l reaches the position a.

18 A normal person's heart, which promotes blood flow with a power of 1.5W, and then does work within 90 minutes. You can use these functions () on high school students with a uniform mass of 50 kg at high altitude (G = 10N/kg).

A.810j2.7m b.810j27m

c . 8 100j 162m d . At 8 100j 16.2m

Second, fill in the blanks (19-2 1 2, 27, 28, 22-26, ***42) 19. Sales? Food trolley on the train (figure). If the goods are placed in an obstacle of the car and a salesman presses Barre in this round, then the trolley can be regarded as a lever fulcrum _ _ _ _ (write a letter). When the rear wheel encounters an obstacle, the salesman releases Barre, and when the fulcrum is _ _ _ _ _ _ _ _, the car can be regarded as a lever.

20。 Many people like to design and participate in the "domino effect" of activities (mixing dominoes at a certain distance, the first domino is pushed down, and all dominoes will be arranged in descending order), in which the physical principle is that this part of energy converted from dominoes into greater energy in autumn is transferred to the next domino, and the dominoes are pushed down faster and faster in the next domino autumn. (kinetic energy/gravitational potential energy)

2 1。 A hydrogen-fueled car independently developed in Shanghai uses hydrogen instead of gasoline. In one experiment, the car traveled in a straight line at a constant speed for 5 minutes with a horizontal ground of 2400N and a traction of 9000 meters. The resistance of the vehicle in the horizontal direction is n, and the power of the vehicle reaches W.

22, as shown in the figure, are connected in series, so L2 of L 1 must be closed; Therefore, L 1 and L2 are connected in parallel in the circuit, and it must be closed.

23。 Student B, in the pole climbing competition, climb to the top of the pole (pole length). The weight ratio between A B and 9S 12S and B is 6: 05, and the work done by B man climbing to the top of the pole is equal power ratio.

24。 When the internal combustion engine is working, the time in the compression stroke can be changed and converted into energy in the process of mutual conversion between two kinds of mechanical energy and internal energy; The other is in the stroke, which can be converted into flywheel speed of single-cylinder four-stroke gasoline engine 1800r/min and working time of two-stroke gasoline engine.

25。 As shown in the figure, the blower blows not only cold air but also hot air, which can simplify the circuit. In the picture, the wire plug of blower B is plugged into the power socket, and the blower blows out the wind as long as the switch Sl is turned off; Switches S 1 and S2 are closed, and the wind is blown by the blower. (cold/hot)

On 26th, with Xiao Ming's help, their parents measured the temperature near his home and the temperature of the deep-water pond water every half hour at 7: 00 in the morning, and drew a temperature-time image according to the recorded data, as shown in the figure. It can be seen that the B line in the figure is small, and the graph with the temperature change of _ _ (air temperature/water temperature) is the reason for the small temperature change.

27。 Of the two toilets at the back of the carriage, only two toilets have closed doors (the latch is equivalent to a switch), and the logo with luminous indicator light will show "toilet". Passengers are reminded that the symbols of the internal components of the two toilets are connected to the circuit diagram required by the design.

28。 Chopsticks are traditional dining tools in China. They use the lever principle, as shown in Figure A, and use chopsticks as ABC fulcrum to absorb the forces in the directions of resistance arm L2 and F 1 F2 in Figure B.

8 points for answering and exploring (29 questions, 30 questions, 3 1 22 minutes)

29。 As shown in the picture, A, Hou Bin, the last torchbearer at the opening ceremony of the 2008 Beijing Paralympic Games, climbed to the bottom of the torch platform with their strength and finally lit the flame. The lighting ceremony fully embodies the courage and spirit of self-reliance and hard struggle of the disabled. It is known that the total mass of wheelchair is 80 kg, the climbing height is 39M, and the duration is about 3 minutes and 20 seconds.

(1) If the extra power of the mechanical device is not counted, what is its average power consumption?

(2) Xiao Ming saw that torchbearers were difficult to climb, and thought that the class of physics college could save energy through pulley block. Xiao Ming is standing on the ground, as shown in Figure B, and Hou Bin, the torchbearer of the pulley block, is the most suitable. What is the reason?

(3) If the mechanical efficiency of the pulley block is 80%, how much does Xiao Ming pull at least? (g = 10N/kg)

Go home on weekends after installing a solar water heater. It was just an observation activity: Xiao Ming measured the temperature of tap water at 20℃ with a thermometer in the morning, and then sent it to the water heater tank filled with water. At noon, the temperature in the water tank is 45℃, and the volume of the known water tank is 200L L, looking for:

(1) Water quality and heat absorbed by water in the water tank. 【 The specific heat capacity of water is 4.2× 103J/(kg? C)]

(2) If the heat absorbed by water is used to provide combustion gas, and the thermal efficiency of the gas stove is 40%, is it necessary to at least burn gas? (q = 4.2× 107J/kg gas calorific value)

3 1。 The detection mechanism detects the braking performance of the automobile. The following experiments were conducted in the same place:

(1), with different speed limits, the measured data are shown in figure A below. The action distance is the braking distance when the driver finds out that the situation determines the braking. When the vehicle passes the car brake pedal parked at a distance, the vehicle slows down. If the driver is driving at a speed of 60 kilometers per hour, from the situation found, he decides to stop and brake at a distance of meters.

(2) There are two kinds of braking:

Brake, the wheels can't roll, they can only slide until the car.

Brake, the wheels continue to roll, but the rolling speed slows down until the car.

Figure b reflects the comparison of the braking distance of the mode brake. As can be seen from the figure, the braking mode is shorter with the same speed.

(3) Detection shows that the speed of two cars is the path taken by car A to brake B, and the distance between the brake car and the obstacle is equal (the distance is less than the larger S 1, as shown in the figure), which affects the damage degree of obstacles on the car by (A/B) and the curve describing the reasons (together with Figure B).

question

Study on the Quality of Mid-term Examination in the First Term of 2009-20 10 School Year

Reference answer for ninth grade physics exam

, multiple-choice questions (paper 2, ***36 points. ) 1 2 3 4 5 6 7 8 9 10 1 1 12 13 14 15 16 17 18

Answer CCDBBCBCBDBADBACDD

Second, fill in the blank story title (each blank question 19-2 1, 22-26 each blank question 2, each blank question 2, ***42).

19。 Civil architecture and energy

20。 Gravity potential energy kinetic energy

2 1.2400n 2. 16× 107j 7.2× 104 w

SL 22 .S3 S2 23.6:5 9: 10

24 mechanical action 60 15

25。 hot and cold

26。 The temperature of water is higher than that of hot water, and it absorbs heat slowly.

27 28

Answer and discuss 8 points (29 questions, 30 questions, 3 questions122 questions) BR/& gt；; 29。 Solution: (1)P = W/T = GH/T = MGH/ ton ................................................ 1.

= 80kg×10n/kg× 39m/200s ......................................1point.

= 156W ...................................................

(2) d .................. 1 pulley block .....................................................................1.

Pulling direction saves effort. ................................................... 1 min.

(3)√η= W Useful /W Total = GH/FS = GH/4fh = g/4f .................................1min.

∴ f = g/4η = (80kg of 65438 +00n/ kg) /(4x0.8) = 250N...............2.

30 (1) m = ρ v =1.0×103× 200×10-3 = 200kg ....................................... 2 stars.

Q Bubble = cm δ t = 4.2×103× 200× 25 = 2./kloc-0 /×107j ..................................

(2)Q absorption = MQ×40%%

M = = kg =1.25kg ........................... 2 points.

3 1( 1)35(2) brake (3)B car, because the kinetic energy (speed) of the car at this time. (2 per space)