Putting a pulley on the bottom of the water, how can you measure the buoyancy and be easy to operate without letting the pulley move?

2011 Physics Compilation -----Mechanical, Function and Energy Department

, Multiple Choice Questions

(Lanzhou) 9. The friend shown in Figure 3 It is correct to slide along the slide at a constant speed (ignoring air resistance)

A. Affected by gravity, supporting force, sliding force and friction force*** all at the same time

B. Affected by gravity, support force and friction force *** the same effect

C. Gravity potential energy conversion energy internal energy

D. Gravitational potential energy decreases and mechanical energy changes

(Lanzhou) 12. As shown in Figure 5, objects G1 and G2 with the same volume are hung on separate levers. The levers at both ends are in a balanced state. If the two objects G1 and G2 are both immersed in water, then

A. Leverage remains balanced B. The lever can balance the sinking of end A

C. The lever can balance the sinking of end B D. Determine the leverage status

(Weifang) 6. As shown in the figure, the ball moves along the orbit from stationary point A to point D, ignoring air resistance and friction

Forces can only transform into potential energy. Then

A. The energy at ball A is equal to the energy at D

B. The energy of ball A is energy of ball D

C. The mechanical energy at ball B is greater than the mechanical energy at C

D. The mechanical energy at ball B is equal to the mechanical energy at C

(Suzhou) 12. As shown in the figure, a 10N pulley lifts a 50N object

at a constant speed. When calculating friction, it should be the same as the F energy value of the pulling force

A. 20N B. 25N C. 30N D. 35N

(Linyi) 7. The explanation is correct

A. The fixed lever can save effort B. The fixed pulley can both save labor and change the force direction

C. Pulley It can both save effort and change the direction of force. D. Pulley = group can both save effort and change the direction of force

(Quzhou) 17. The tree support shown in the picture is placed on the B end of the support. The tightening belt is kept at a certain distance from the tree root C and the A end is fixed on the tree trunk. Use the hydraulic device to push the trunk force to support the trunk point A at the position shown in the picture

A. Received thrust along BA

B. Being pushed perpendicular to AB

C. The thrust force arm AB

D. The thrust force arm BC

(Nanchang) 5 As shown in Figure 4, the vertical force F of 10N acts on the weight A and rises at a constant speed in the vertical direction. The lifting speed of the weight A is known to be 0.2m/s. Depending on the weight of the pulley, the weight of the rope and the friction between the rope and the pulley, the object's gravity pulley will rise at different speeds

A. 20N 0.4m/s B. 20N 0.1m/s

C. 5N 0.4m/s D. 5N 0.1m/s [Source: #科#网Z#X#X#K]

(Zhenjiang) 12. The hook code and the water-filled test tube are at rest on both sides of the fixed pulley (calculating friction, rope weight and air resistance)

Use your finger to flick the bottom of the test tube before the test tube is in contact with the fixed pulley

A. To speed up transportation B. Transport towards deceleration

C. Move toward uniform speed D. Shuodu

(Zhanjiang) 11. As shown in Figure 4, the wooden block is placed next to the compression spring and the spring is released. The wooden block is moved to the right along the horizontal plane and stops some distance away from the spring wooden block. The list is correct

A. The weight exerted on the wooden block by transporting the wooden block causes work to be done by the wooden block

B. The elastic force of the spring wooden block causes the wooden block to move from rest

C. The friction force on the wood block changes the movement state of the wood block

D. The wooden block finally stopped running due to the loss of spring elasticity

(Huanggang) 18. The figure shows the four ways of using a simple machine to lift the same object at a constant speed (taking into account the friction of the machine's own weight) and the force required

(Huanggang) 19. Analysis of raindrop falling at a uniform speed in the air (considering the change in the mass of the raindrop and the buoyancy force of the raindrop) is correct

A. Raindrops are acted upon by balancing forces B. The mechanical energy of a raindrop remains variable as it falls

C. Raindrops are affected by gravity and resistance D. Raindrop gravitational potential energy conversion energy

(Henan) 14. As shown in Figure 7, a horizontal pulling force of F=50N is used to pass through the pulley to move an object A weighing 200N horizontally to the right for a distance of 3m at a constant speed

A. The pulling force F does 150J of work

B. The tensile force F is 300J

Gong

C. Gravity does 600J of work

D. Gravity does 1200J of work

(Henan) 11. Colorful balloons for the World Expo evening are accompanied by festive music and the balloons rise at a constant speed

A. Can convert potential energy into mechanical energy change

B. Can convert potential energy into mechanical energy and increase

C. Can change potential energy to increase mechanical energy

D. Energy can be changed into potential energy, which can be changed into mechanical energy

(Texas) 5. As shown in Figure 3, four forces are applied at point A to keep the lever in a balanced state

A. F1 B. F2

C. F3 D. F4

(Texas) 1. Swinging is a kind of entertainment and leisure in our national sports competitions. The high point on one side of the swing is the same as the high point on the other side.

A. Gravitational potential energy decreases B. Can increase directly

C. Can decrease first and then increase D． Gravitational potential energy decreases and increases first

(Laiwu) 7. Lift A is mechanically more efficient than lift B. If an object of the same mass is lifted to the same height at a constant speed, then

A. B. Lifting heavy objects requires more effort

B. A. The extra work done by the lift motor is relatively high

C. The total work done by the lift motor A is less

D. The total work done by the elevator motor in B is less

(Laiwu) 4. A driver driving a truck on a certain road section was stopped by the police for speeding. The driver said: First, the speed was 70km/h. The driver said: The speed limit of the car is 80km/h, but the speed limit of 60km/h is reasonable! Let the driver explain from a physical perspective because

A. The inertia of an object is related to its speed and mass

B. Friction is related to speed and mass

C. Object energy is related to speed and mass

D. Pressure is related to speed and quality

(Meizhou) 8. List the object's gravitational potential energy conversion energy

A. Skydivers fall into the sky at a constant speed

B. Hot air balloon lift

C. A car's traveling distance on a level road at a constant speed

D. Shot put free fall

(Jixi) 12. Li Nina, a player from Heilongjiang Province at the Vancouver Winter Olympics, won the silver medal in the freestyle skiing competition. The air resistance listed in the competition trajectory chart is correct ( )

A. All the gravitational potential energy in the journey from point a to point b is converted into energy

B. The velocities of point a and point c are equal to zero gravity potential energy

C. Conversion energy of gravitational potential energy from point c to point d

D. Points a and e are all at rest and have equal mechanical energy

(Jixi) 7. Weightlifting competitions require athletes to hold the barbell in the air for at least 3 seconds

Within 3 seconds

A. The barbell is supported by gravity and has a balance force ( )

B. The balance force of the gravity surface support force exerted by the athlete

C. The athlete applies force to the support barbell

D. Barbell athlete's pressure support force and balance force

2. Fill-in-the-blank and experimental questions

(Wuhu) 9. As shown in Figure 5, the free end of the crane wire rope used in a factory for lifting cargo is lifted vertically for 3m at a constant speed with a force of 2000N and the cargo is 6000N. Then the cargo is moved horizontally for 6m. The work done by the gravity of the cargo is J; the cargo is lifted vertically. The work done by the gravity of the cargo J The traveling pulley block improves the efficiency of cargo machinery

(Zhenjiang) Picture A Draws a schematic diagram of the gravity exerted on object A The tensile force F and the stress arm l.

(Wuhu) 17. The fixed pulley is used relative to the lever. As shown in Figure 8, a rope is used to pull the hook code along the inclined direction through the fixed pulley. The known hand pull force F is the hook code gravity G

(1) Please draw the lever fulcrum O and draw the pulling force. F. Hook code gravity G and force arm (keep the traces of drawing);

(2) If friction, pulley weight and rope weight are considered, please use the lever balance condition to deduce: F＝G

(Wuhan)17． (5) Figure shows the experimental device related to the mechanical efficiency of the same inclined plane

The experiment uses a spring dynamometer to pull the same block along the slope with the same roughness to perform uniform linear motion. Experimental department data:

Experiment

Count the Incline

The weight of the block with the degree of inclination

G/N [Source: Zxxk.

Com] Incline height

h/m [Source: Kewang] Tension force along the slope

F/N Incline

s/m Mechanical efficiency

1 Slower10 0.1 5.0 1

2 Steeper10 0.3 6.7 1 45%

3 Steeper10 0.5 8.4 1 60%

⑴Ming Exploring the relationship between the mechanical efficiency of inclined planes. The first experiment of the mechanical efficiency of inclined planes. The internal energy of the inclined plane of the block increases by about J

⑵ Analysis of table data. Conclusion: The roughness of the inclined planes is the same. The steeper the inclined planes, the higher the mechanical efficiency. To explore the mechanical efficiency of inclined planes and the relationship between them. The relationship between the roughness of the inclined surface should remain variable

(Zhanjiang) 18. The phenomenon of high-altitude paraboloids is called hanging city sky pain. According to reports: A 30g egg was thrown from the 18th floor and broke the bones, causing death on the 25th floor. It is known that the gravitational potential energy of the egg is converted into the gravitational potential energy of _________ off the path_____________

(Jining). 7. An experimental group explores the experimental device that affects the mechanical efficiency of the pulley block. The experimental data table shown in Figure 7 is as follows: Friction comparison of 12 and 12 experimental data shows that the mechanical efficiency of the pulley group is related to

; Comparing the experimental data of 13 to see that the mechanical efficiency of the pulley group is related to

(Taizhou). (6) Use the pulley block shown in Figure 6 to lift a heavy object. It is known that the object weighs 200N and a pulling force of 125N is applied to the pull rope to make the object rise 2m at a constant speed within 5s. Find:

(1) The work done by the pulling force and the pulling force power;

(2) Mechanical efficiency of pulley block.

(Sea) 13. If an object moves 2 meters along the horizontal plane with a horizontal pulling force of 5 N in 10 seconds, the pulling force will do _________joules and the power will be _________watts; if the object weighs 20 N, the gravity object will do work_______joules

(Anhui) 8. The simplified schematic diagram of the AOB mechanical equipment shown in the figure. I look at the lever (self-weight gauge). It is known that AO=2OB. Fix point O so that OB is in a horizontal position. End B is hung with a weight of 40N. For an object to rotate the lever, at least end A needs to be applied. F=______N. Try to draw force. F Xiang [Source: Zxxk.Com]

(Anhui) 21. A certain type of car with a rated power of 6×104W driving on a level road at a constant speed and a resistance of 1800N is required to find:

(l) The traction provided by the engine;

(2) Driving speed;

(3) Work done by traction force after driving for 5 minutes

(Lanzhou) 33. (6) The object weight shown in Figure 23 is G2000N. Inclined surface 5m high 3m inclined surface pulley block device total machinery Efficiency 80 If a heavy object is pulled along an inclined plane at a speed of 0.2m/s, find:

(1) The required pulling force F is less (2) The total mechanical power is less

(Chongqing) 21. Caribbean On the afternoon of November 12, 2011, a strong earthquake with a magnitude of 7.3 occurred in the island. Taigang, the capital, and all districts were seriously affected. The international community extended a helping hand and offered humanitarian assistance to the sea. During the search and rescue operation, the rescue team found that a block of about 1.8 tons of building materials was blocked. The contact area between the material and the surface in the narrow space is about 1.5m2

(1), the surface pressure of the building material (g is 10N/kg)

(2), due to limited conditions, the rescue team can The pulley building materials shown in Figure 17 are lifted off. If the mechanical efficiency of the pulley group during the lifting distance is 80%, find the tensile force exerted by the free end of the distance rope

(3). If the material is pulled at a speed of 0.01m/s, the tensile power will be Shao

(Huanggang) 24. In the picture on the right, the geometric dimensions of the escalator section of a shopping mall's escalator are shown. The mass is 50kg. The escalator is on the second floor of the shopping mall building. It is known that the escalator travels at a constant speed of 1m/s, then the work done by the escalator is ________JJ and the work power is ________W. The number of station escalators increases escalator efficiency ________ (fill in change, change or change). If the faster escalator in China travels at the same speed as the in-phase escalator 1m/s and the escalator walks in the same direction, the time required to reach the second floor will be ________s

(Huanggang) 25. The picture on the right shows a road drilling machine (commonly known as a woodpecker) for road maintenance. This machine uses a compressed gas plug drill to drill into the road surface. Gas plunger________can convert___

_____ can; drill and make a cone_______________________________; If the woodpecker diesel engine has a mechanical efficiency of 40%, it will completely burn 50 kg of diesel with external work of ________J (diesel calorific value 4.3×107J/kg).

(Suzhou) 26. (8) The slope shown in the figure is S=10m and the height is h=4m. Use a 100N object with a thrust force F along the incline to push the top B from the bottom A of the incline at a constant speed. The moving object overcomes friction

Does 100J of work. Find:

(1) The movement overcomes the gravity of the object to do work;

(2) Incline mechanical efficiency;

(3) Thrust F.

(Yancheng) 16. Explore the balance conditions of the lever. If the right side of the lever is high and the left side is low, adjust the balance nut on the left side to ▲ to balance it in the horizontal position. As shown in the picture, hang a 3

hook code with an average weight of 0.5N at the 20cm scale on the left side of the fulcrum. At the 15cm scale on the right side of the fulcrum, use a spring dynamometer to pull the lever to make it horizontally balanced. To make the spring dynamometer display

the tensile force of the spring dynamometer, read the number N in the direction

.

(Yancheng) 20. An industrial fixed pulley weighs 240N and lifts the object 4m in 5s with a pulling force of 250N at a constant speed.

Cheng Gonggong ▲ J pulling force work power ▲ W writes that the pulling force is equal to the weight of the object:

(Quzhou) 26. The giant celadon bowl with a diameter of 8 meters in the Zhejiang Expo Museum contains 6 tons of water lights. The blue waves in the celadon bowl are accompanied by the melodious music of silk and bamboo. Visitors feel like they are in a painting of Jiangnan

(1) Visitors look at the rippling blue waves on the water and the lights on the water▲;

(2) A giant ring-shaped lift platform around the celadon giant bowl. The tourist lift platform is in a circle. The lift platform rises to see the scene inside the celadon giant bowl. A certain lift platform has 80 tourists rising 3 meters at a constant speed. If the mass of each tourist Calculating 60 kilograms, the work done by tourists for the lifting platform is ▲ Jiao

(Xianning) 13. As shown in Figure 5, the fitness movement object A has a mass of 4kg and the pulley friction meter swings the ankle in the direction so that the string pulls the object A and slowly (uniformly) lifts the ankle. If object A is lifted 0.3m at a constant speed, the work done by object A will be J power W

(Xianning) 14. The pole vaulting event is a highly technical sport. The complete process is simplified as shown in Figure 6. The three stages are as shown in Figure 6: holding the pole, taking off and rising, and falling over the pole to reach the high point. The distance can be transformed; the falling distance can gradually increase

(Suqian) twenty three. A reporter reported: Looking at the botanical garden, I reached out and picked up a piece of wood with a root of about 3m and a radius of about 0.2m. I gently lifted the top and played with it. Picture A: The wood ball is made of balsa wood - the density of balsa wood is 0.2g/cm3. (g=10N/kg)

⑴ Please provide data calculations through the text and answer whether the report is true.

⑵ If the wood is placed vertically on the horizontal plane as shown in Figure B, calculate its surface pressure;

⑶ If the pulley set shown in Figure C is used to lift the wood to the car at a constant speed, the pulling force used is F314N. Find the mechanical efficiency of the pulley block.

(Nantong) 32. (8) As shown in the figure, the master worker uses a fixed pulley and pulley block. The pulley block weighs 500N and the box lifts 5m at a constant speed. The pulley mass is 8kg. Calculate the rope weight and friction and take g=10N/kg.

(1) The picture uses pen lines instead of strings to assemble the pulley block.

(2) What is the pulling force of the box-lifting rope?

(3) The mechanical efficiency of the box-lifting pulley group is low?

(Zhanjiang) 23. The stevedores of Zhanjiang Port use the pulley block shown in Figure 1l to lift the cargo with a mass of 80 kg at a constant speed. The pulling force F500N on the free end of the rope is 4m at a constant speed in 50s. Find: (g is taken as 10N/kg)

(1) The cargo is stationary before lifting The surface-to-surface contact area is 0.04m2. Find the surface pressure of the cargo.

(2)The speed of the free end of the lifting rope.

(3) Pulling force F power.

(4) Mechanical efficiency of pulley block.

40． (5) Physical education includes physical knowledge table Yang Weitong physical education test results

Please provide information according to the form.

Column calculation: (g takes 10N/kg)

(1) Yang Weitong’s average speed in running 100m?

(2) Figure 14 Yang Weitong’s 500NA point weight, please refer to the figure data Find the support force F;

(3) If Yang Weitong uses a 4s barbell to lift 2m, the power of lifting the barbell will be less?

(Texas) 15. The rope weight of the device shown in Figure 22 is Friction meter The loader's weight is 800N and the cargo is lifted to a high place. The rope tension is F1500N. The cargo rises 5m at a constant speed in 1 minute.

(1) Please draw the rope winding;

(2) Find the mechanical efficiency of the pulley block;

(3) If the weight is 600N and the weight is lifted 5m, find the pulling force and work

(Meizhou) 16. Figure 5 shows the experimental device for measuring the mechanical efficiency of the pulley block. The total weight of the hook code is 6N. The experiment requires pulling the spring dynamometer vertically and at a constant speed. From the figure, the pulling force N is known. If the hook code is raised to a height of 8cm, the spring dynamometer moves cm. The mechanical efficiency of the pulley block is ( Number of reserved digits)

(Meizhou) 26. The mass of object A shown in Figure 14 is m = 12kg. Tensile force F. Object A is moving in a straight line with a speed of 0.1m/s on the horizontal plane at a constant speed. The spring dynamometer indicates 12N. Ignore the friction between the pulley and the rope and the gravity of the pulley and spring dynamometer. The rope is enough to find:

(1) Friction force f between object A and the horizontal surface;

(2) Tension force F;

(3) Object A moves for 10 seconds Work done by the pulling force F

(Jixi) 25. Scene from the TV series "Three": A group of soldiers pull a lever and throw stones towards the enemy camp. The lever should act on point A in the direction of (fill in a, b or c) (fill in a, b or c) (Jixi) 33. To get good results in the physical education test, you should do physical exercise every day

(1) First jog along the 200m track to exercise 6:006:10***The average speed of running 12 laps is about less

[Source: .ke.net]

(2) The weight of the skipping rope is 60kg at the end of jogging. Each jump height is about 5cm. Each jump requires about a few joules of work to overcome gravity

(3) Take the 1 minute jump rope test and jump 160 in the rain and jump 100 in the morning. Question: The test results are the same as the work done.

Function and mechanical energy 2

13. (2011 Guangzhou 4) The escalator at station A moves at a constant speed of 0.5m/s and at station B, the escalator moves at a constant speed of 0.7m/s. If A and B have equal masses, A can do (optional increase,

change, decrease). The position of a certain moment is shown in Figure 13

At this moment A's gravitational potential energy B's gravitational potential energy A's machine

Mechanical energy B's mechanical energy. (Choose to fill in at, equal to,

with). If you are walking on an escalator and suddenly stop moving your armor, your armor will lean forward

Original

Answer: 13. The change is equivalent to the friction between your armor and feet immediately stopping your body and continuing to move forward due to inertia

20. (2011 Guangzhou) As shown in Figure 23 (the rope around the pulley is not shown), a 600N force pulls the rope end of the pulley for 10 seconds, causing the rope end to move 1.5m, and the weight rises at a constant speed

0.5m Known pulley machinery Efficiency 70 (g=10N/kg).

(1) Tensile power

(2) Lifting weight

(3) Draw the pulley and wind the rope according to the question.

21. (2011 Anhui 8) A certain model of automobile engine with a rated power of 6×104W is running at a constant speed on a level road and the resistance is 1800N. The rated power of the car is driving at a constant speed. Find:

(l) The traction provided by the engine;

(2) Driving speed;

(3) Work done by traction force after driving for 5 minutes

Answer: 21. (1) Since the car is traveling at a constant speed and is subject to the traction force F =f=1800N due to the balance force (2)

(2) From P=Fυ: the car is driving at a constant speed υ=P/F= 6×104W /1800N= 33.3 m/ s (3)

(3) w = Pt = 6×104W×5×60s=1.8×1

07J

5. (2011 Anhui 2) The current earthquake occurred in the scene where the emphasis was placed on strengthening and repairing the house. See the scene in the picture. Suppose the work is slowly lifted by 4m using a pulley with 50kg of cement. The tensile force used on the roof is about 300N. The efficiency of the machine is about __________

. 7. (2011, Jining 2) An experimental group explored the experimental device that affects the mechanical efficiency of the pulley block. The experimental data table shown in Figure 7 is based on friction. Comparing 12 and 12 experimental data to see the mechanical efficiency of the pulley block; comparing 13 and 13 experimental data to see the mechanical efficiency of the pulley block. Related

7. (2011 Metropolis 2) As shown in Figure 2, Li Xian took a visit to the East Crown of the Maritime Expo and took the elevator in the elevator building at a constant speed. Li Xian

A. Can continue to increase

B. Gravitational potential energy continues to increase

C. Can convert gravitational potential energy

D. Gravitational potential energy conversion energy

20. (2011 Du 4) To compare physics with things, you need to introduce the same physical quantity. To compare the speed of movement of objects, you need to introduce speed; to compare the speed of work, you need to introduce; to compare the effect of pressure, you need to introduce

26. (2011 Suzhou 8) The inclined plane shown in the figure is S=10m and the height is h=4m. Use a 100N object with a thrust force F along the incline to push the top B from the bottom A of the incline at a constant speed. The moving object overcomes friction

Does 100J of work. Find:

(1) The movement overcomes the gravity of the object to do work;

(2) Incline mechanical efficiency;

(3) Thrust F.

20. (2011 Suzhou 3) Construction workers use a 50N horizontal thrust cart to move the cart forward at a constant speed of 15m on the horizontal plane. The cart is subject to resistance ▲ N. Even after the thrust vehicle is withdrawn, the vehicle can still continue to move forward 0.5m due to the vehicle equipment ▲. Describe the work done by a construction truck traveling 15.5m forward ▲ J.

Answer: 20.50 Inertia 750

25. (2011 Taizhou 6) Use the pulley block shown in Figure 6 to lift a heavy object. It is known that the object weighs 200N and a pulling force of 125N is applied to the pull rope to make the object rise 2m at a constant speed within 5s. Find:

(1) The work done by the pulling force and the pulling force power ;

(2) Mechanical efficiency of pulley block.

4． (2011 Yantai 2) Coaster is not a thrilling entertainment and leisure activity. The low end of the roller coaster track rises and the high end speeds up (Figure 3). The calculation of energy loss is correct

A. The mechanical energy at point a is the mechanical energy at point b

B. Point d energy, point b potential energy, point c mechanical energy

C. The ab process energy decreases the potential energy and increases the mechanical energy change

D. From bc process energy increases potential energy decreases mechanical energy change

30. (Yantai 10, 2011) As the level of social development increases, housing conditions improve. Ming's family recently purchased a new house to help his father transport 600N of decoration materials to a 6m high building. Ming used the pulley block design in physics class to design the material transportation case shown in Figure 20A

Such a question is meaningless

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