Fill in the blanks
1.(20 10. Zhenjiang) On June 4th this year, CCTV reported the fourth salvage of the suspected residual stone of Yiheming in Jiao Shan, which aroused Xiao Wei's interest in further exploring buoyancy knowledge. He used spring dynamometer and beaker to explore, and the main process and measured data are shown in the figure. The metal block is slowly immersed in the water. From the moment when the metal block touches the water surface to the moment when it is completely submerged, the pointer of the spring dynamometer becomes smaller. After the metal block is completely submerged, the buoyancy is 1 N, and the pressure of water on the metal block increases with the increase of depth.
27.(20 10, Lishui city) The picture shows a water bike made by a classmate. She installed eight closed empty buckets (each with a volume of 0.02 m3) on the ordinary bicycle and several plastic sheets on the rear wheel of the bicycle. When students ride bicycles at a uniform speed on the water, except for the boiling water volume discharged by wheels and plastic sheets, about half the volume of each bucket is immersed in water on average. At this time, the buoyancy of the water bike is about 800 N.
25.(20 10. Jilin) The mass of a fresh quail egg is11g. If immersed in a measuring cylinder containing 50 ml of water, the water surface rises to the position shown in the figure, and the density of quail eggs is 1. 1g/cm3 (or 1.653). Gradually adding salt into the water and gently stirring until the quail eggs are in a suspended state, during which the buoyancy of the quail eggs becomes larger (or increased); At this time, the density of brine is 1. 1g/cm3 (or1.1×103kg/m3).
(20 10. Yuxi) When measuring the density of a liquid with a densimeter, as shown in Figure 6, its gravity and buoyancy are equal. The greater the density of the liquid, the smaller the volume of the liquid it displaces, and the higher the position of the densimeter (choose "high" or "low").
1.(20 10 Enshi) Workers lift the object A from the water at a uniform speed through the device shown on the right. It is known that the weight of object A is 140N, and the worker's own weight is 600N N n. At this time, his pressure on the ground is 550N N, regardless of the resistance of water to the object, the friction between rope and pulley, and the gravity between pulley and rope. Then the buoyancy of water to object a is 40 n.
2.(20 10 Huzhou) 20 10 On the morning of May 28, American man Jonathan tied himself to a chair with a bunch of helium balloons and sent himself to the sky (for example,
Figure), realize the feat of crossing the English Channel by helium balloon for the first time.
(1) Hydrogen is less dense than helium, and Jonathan uses helium instead of hydrogen as the filling gas.
The body is flammable because of hydrogen.
(2) If the total volume of the whole device is 100 m3 and the air density is 1.29 kg/m',
Then the buoyancy of the whole device subjected to air is _ _1290 _ _ n.
(3) Jonathan cut the ropes of several balloons in order to land, and the whole device suffered.
The buoyancy of _ becomes smaller _ _ (optional "bigger", "smaller" and "unchanged").
3.(20 10 Taizhou) At the 2009 World Swimming Championships, German swimmer paul biedermann put on a high-tech conjoined swimming book. The surface of this swimsuit is made of light polymer material, which can capture air and increase the volume of boiling water, thus increasing the buoyancy of athletes in the water. It can also make athletes smooth, thus reducing the friction between human body and water.
Second, multiple choice questions
1.(20 10. Ningxia) About the buoyancy of objects, the correct statement is (b).
A floating object is more buoyant than a submerged object. B. The greater the density of the object, the greater the buoyancy.
C. The greater the volume of liquid displaced by an object, the greater the buoyancy it will receive. D. the buoyancy of an object in a liquid is related to its depth.
2.(20 10. Xiangtan) In the experiment to study the ups and downs of objects, eggs were put into a glass filled with water and then sank to the bottom of the water. In order to make the eggs float, the measure that can be taken is to add a proper amount of (C) to the cup.
A. hot water b alcohol c salt d ice water
3. (Changzhou, 2065438+00) In May 2065438+00, the American submarine Poseidon successfully dived in the Pacific Ocean 1 1000m to explore the deepest Mariana Trench in the world. In the process of diving, the volume of the submarine remains unchanged, and the changes of its pressure and buoyancy are (B)
A. the pressure gradually increases and the buoyancy gradually increases.
B. the pressure increases gradually and the buoyancy remains unchanged.
C. the pressure gradually decreases and the buoyancy gradually decreases.
D, the pressure decreases gradually, and the buoyancy remains unchanged.
4.(20 10. Changzhou) With global warming, icebergs floating on the sea surface are gradually melting. In order to explore whether the sea level changes after the iceberg melts, Xiao Ming puts a piece of ice into strong salt water, and the ice is floating, and the liquid level is as shown in the figure. After the ice melts, the liquid level in the cup will be higher than that before melting (B).
A. unchanged
B. Elevate
C. decline
D. unable to judge
5.(20 10. Lianyungang) As shown in the figure, ice floats on the water surface and sinks in alcohol, so the following statement is correct (b).
Answer: The buoyancy of ice subjected to water is greater than the gravity of ice.
B the buoyancy of water to ice is equal to the gravity of ice.
The buoyancy of ice subjected to alcohol is equal to the gravity of ice.
D. The buoyancy of alcohol to ice is greater than the gravity of ice.
8.(20 10. Chuxiong Prefecture) Two identical containers contain two liquids, A and B, respectively. Put two identical balls into two containers respectively. When the two balls are at rest, the liquid level is even, and the position of the balls is as shown in the figure. The pressures of liquid A and liquid B on the bottom of the container are P A and P B respectively, and the buoyancy of the two balls in liquid A and liquid B is F A and F B respectively, so their relationship is (A).
A.P A > P B F A = F B。
C.P A > P B F A > F B D
10.(20 10. Guang 'an City) In the following cases, the buoyancy of an object increases (C).
A. Swimmers run from the sea to the beach B. Ships sailing from the Yangtze River estuary to the sea
C. ships loading at the dock. A submarine that dives into the deep water under the sea.
10.(20 10. Yancheng City) As shown in the figure, a plastic bag, regardless of the thickness of gravity, is filled with more than half a bag of water, and it is sold.
Hook the spring dynamometer and slowly immerse it in water until the plastic bag and container (a) reach the water surface.
The water is flat. Indication of spring dynamometer in this process
A. gradually reduce to zero B. reduce first and then increase.
C. always keep the same d. stepup
1.(20 10. Liuzhou) As shown in Figure 5, three small balls with the same volume are still in the water, and their buoyancy is D.
A.FA & gtFB & gtF c
B.FA & ltFB & lt Football Club
C.FA & gtFB=Fc
d .FA & ltFB=Fc
7.(20 10. Dezhou City) At present, the voice of making China's own aircraft carrier is getting louder and louder, as shown in Figure 5, which is a picture of a Chinese aircraft carrier provided by a netizen. After the carrier-based aircraft of the aircraft carrier leaves the aircraft carrier, there are (a)
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.
(20 10. Guilin) As shown in the figure, two identical containers are filled with water, and a wooden block with a volume of 50cm 3 and a density of 0.5x 103kg/m3 floats on the water surface. The following statement is true: C.
A. Buoyancy of wood blocks is equal to their own gravity when floating, and 1/3 volume is exposed to water.
B. When the block is slowly pressed down until it is submerged, the buoyancy of the block remains unchanged.
C, all the wood blocks are pressed into the water, and the water pressure at the bottom of the two containers is equal.
D, after the wooden block is taken out, the pressure of the two containers on the horizontal desktop is equal.
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(20 10. Tianjin) Two solid spheres A and B with equal mass, with densities ρ A and ρ B respectively, ρ A: ρ B = 3: 2. Put them in deep enough water, and the ratio of buoyancy of ball A and ball B at rest may be BD.
A.3:2 B. 1: 1
C. rho water: rho B. rho water: rho a.
(20 10 Urumqi) As shown in the figure, when metal balls of different sizes made of the same material are hung at both ends of the optical lever, the lever is balanced. Immerse them in water at the same time, and the lever remains balanced, then (a)
A. both balls are solid. B. The big ball is solid and the small ball is hollow.
C. The big ball is hollow and the small ball is solid. D. Both balls are hollow, and the hollow parts have the same volume.
Third, drawing questions
1.(20 10. Jiangxi) The submarine expedition returned to a base in the Yangtze River after completing its mission in the East China Sea. Please draw a schematic diagram of the gravity and buoyancy of the submarine during its acceleration and ascent in Figure 12.
Solution: As shown in the figure.
Fourth, experimental inquiry questions
1.(20 10. Hechi) Xiaogang picked up a beautiful small stone in the river. He wanted to know the buoyancy and density of the stone when it sank into the water, so he designed the following experimental scheme.
(1) experimental equipment: small stone, thin thread, overflow cup, water, small beaker and measuring cylinder.
(2) Experimental steps:
A, filling an overflow cup with water;
B, tying the small stone with a thin thread, immersing the small stone into the overflowing cup, and catching the overflowing water with a small beaker;
C, measuring the volume v of overflowing water (or water in a small beaker) with a measuring cylinder;
D. Calculate the buoyancy of small stones, f float = ρ water gV.
(3) After Xiaogang finished the experiment, he took out the small stone from the overflow cup, put it directly on the adjusted balance to measure the quality, and then calculated the density of the small stone. Do you think Xiaogang did this, and the measured stone density was higher than the actual density (choose "big" or "small") because of the large mass (or small volume)?
(3) Large (as long as it is reasonable, points can be given)
2.(20 10. Lianyungang) A classmate conducted the experiment of "Exploring the Factors Affecting Buoyancy" according to the illustrated steps, with a spring dynamometer every time.
The instructions are shown in the figure.
(1) From the data obtained in experimental steps (b) and (c), it can be concluded that the buoyancy of an object is related (related/irrelevant) to the volume of liquid displaced by the object.
(2) From the data obtained in the experimental steps (c) and (d), it can be concluded that the buoyancy of an object immersed in liquid has nothing to do with the depth.
(3) According to the experimental data, the buoyancy of an object immersed in concentrated salt water is1.1n. 。
33.(20 10. Hebei) Xiaoming made his own soil densimeter to measure the density of salt water.
Experimental equipment: balance, cylindrical bamboo chopsticks, thin lead wire, beaker, water and salt water to be measured.
Experimental steps:
① A proper amount of fine lead wire is wound around one end of bamboo chopsticks to make a soil densimeter.
② Measure the length L of bamboo chopsticks with a scale.
(3) Put the soil densimeter into a beaker filled with water, and measure the bamboo chopsticks on the liquid surface with a scale after standing.
The length of h 1 (as shown).
(4) Put the soil densimeter into a beaker filled with salt water, and measure the length h2 of bamboo chopsticks on the liquid surface with a graduated scale after standing (or put the soil densimeter into a beaker filled with salt water, and measure the length h2 of bamboo chopsticks submerged under the liquid surface with a graduated scale after standing).
Please complete the above experimental steps and answer the following questions: (ρ water = 1.0 g/cm3, f float = ρ gV row of liquid).
(1) One end of the bamboo chopsticks is wrapped with lead wire, so that the bamboo chopsticks float vertically in the liquid.
(2) The densimeter works under floating conditions. The greater the density of the measured liquid, the smaller the volume of the liquid discharged by the densimeter (choose "smaller" or "larger").
(3) The density expression of the salt water to be measured: ρ salt water = ρ water (ρ water) (excluding lead wire volume).
(4) Xiao Ming calculated the density of brine as 1.05 g/cm3. Suppose the volume of brine in the beaker is 400 cm3, the density of salt is 2.6 g/cm3, and the salt content in brine is 32.5? G. (After salt is dissolved in water, the total volume of salt and water remains unchanged. )
1.(20 10. Harbin) (5 points) When learning buoyancy knowledge, Jiang Ping knew Archimedes principle and its mathematical expression was F float =G row. The classmate wanted to verify it through experiments, so she went into the laboratory and chose a big beaker (or overflow cup), water, spring dynamometer, iron block, small bucket and thin thread to carry out the experiment.
(1) describes her experimental process by sketching;
(2) Please design a form for her to record the measurement data;
(3) Write the process of verification with measured data. (The measured data in the table are represented by physical quantities)
Answer:
Verb (abbreviation of verb) calculation problem
1.(20 10. Jiangxi) During the May Day, Xian Xian brought back a "Little Mermaid" handicraft from the Danish Pavilion of the Shanghai World Expo. He wanted to know the density of this handicraft, so he conducted an experiment. Please calculate according to the experimental data shown in Figure 16: Tips: The density of water is expressed in letters.
(1) The buoyancy of handicrafts at this time
(2) the density of handicrafts
Solution: (1) row m = m 1-m3...( 1)
F float = g row = m row g = (m1-m3) g … (2 points)
(2)m handicrafts = m2-m3...( 1 min)
V Crafts =V Row == (1 point)
ρ Crafts = = ρ Water ... (2 points)
(2.(20 10/0. Hechi) At the beginning of this year, severe drought occurred in most areas of Hechi, making it difficult for people and animals to drink water. Many people need to carry water far away. Xiaoyu put a thin board on the water to prevent water from splashing out of the bucket, as shown in figure 18B, and 3/4 of the board is submerged in the water. If the size of the board,
(1) buoyancy of thin plate.
(2) The bottom of the bucket is under the pressure of water.
(3) If the total load weight is 360N and the contact area between the pole and the shoulder is 20cm2, what is the pressure on Xiaoyu's shoulder?
Solution: (1) From row V =× 200 cm3 =150 cm3 =1.5×10-4m3.
Then the buoyancy of the plate is F float = ρ water gv row...( 1 min).
= 1000kg/m3× 10N/kg× 1.5× 10-4 m3
= 1.5n...( 1)
(2) the water pressure at the bottom of the bucket p = rho water GH (1 min)
=1000kg/m3×10n/kg× 0.35m.
= 3.5× 103 Niu ... (1)
(3) The pressure on Xiaoyu's shoulder P/=
=...( 1 min)
=
=1.8×105pa ... (1min)
22.(20 10. Yancheng city) (9 points) A piece of wood weighs 1600N, has a volume of 0.2m3, and floats on the water, with a g of 10N/kg.
(1) Wood quality;
(2) Density of wood;
(3) Buoyancy of wood.
Analysis: This question requires students to calculate mass, density and buoyancy with simple formulas, which can be done well by students who study hard. The difficulty coefficient is 0.8. The correct answer is: (1)160kg (2) 800kg/m3 (3)1600n.
17.(20 10. Guang 'an City) (8 points) Last week, the school bought a batch of faucets. According to the merchant, the material is copper, and the teacher in the laboratory organized some ninth-grade students to verify the merchant's statement through experiments. They tied a faucet with a thin thread, hung it on a spring dynamometer, and measured its gravity in the air as1.6n. Then they submerged the faucet in water, as shown in figure 14. At this time, the reading of the spring dynamometer was 1.4N(ρ copper = 8.9×/kloc-0.
Q: (1) What is the mass of each faucet?
(2) What is the buoyancy of this faucet submerged in water?
(3) What is the density of these faucets? Is the merchant's statement correct?
Solution: (1) m = = 0.16 kg =160g.
(2)F floating = g-f =1.6n-1.4n = 0.2n.
(3)∫F float =ρ water gV row
∴V row ==2× 10-5m3=20cm3
∴V=V Street = 20 cubic centimeters
∴ρ==8g/cm3=8× 103kg/m3
∫8× 103kg/m3 & lt； 8.9× 103 kg/m3
So none of these faucets are made of pure copper.
A: Omit.
(20 10. Yibin) (12 minutes) Since the autumn of 2009, some areas in southwest China have suffered from severe drought, and many places have to dig deep wells to get water. As the picture shows, Xiao Ming is lifting water from a deep well with a pulley block and a metal bucket. If the material density of the bucket is 8g/cm3, the weight of the bucket is 4kg and the volume of the bucket is 20L ... Xiaoming's pulling force on the rope is f = 25n. Excluding rope weight and friction, the density of water is 1.0× 103 kg/m3, and g is 10n/kg. Try to find out:
How much does the pulley weigh?
(2) When the bucket touches the water, what is the efficiency of the pulley block?
(3) How much force does Xiao Ming exert on the free end of the rope after the bucket is lifted from the water surface of the well and rises vertically at a uniform speed of 0.2m/s?
Answer: (1) The gravity of the bucket is: G=mg=4kg× 10N/kg =40N.
The volume of the bucket is: v bucket = m/ρ = 4kg/(8×103kg/m3) = 5×10-4m3.
The buoyancy of the bucket is f float = ρ water gV row = ρ water gV bucket =1.0×103kg/m3×10n/kg× 5×10-4m3 = 5n.
Pull the rope with bucket: F pull =G-F float =40N-5N=35N.
Because regardless of the weight and friction of the rope, there are two ropes to bear the load, so there are:
F=(F pull +G move) /2, that is, 25N=(35N+ G move) /2, and the solution is: G move = 15N.
(2) The mechanical efficiency of the pulley block when the bucket is exposed to water.
=70%
(3) When the bucket is full, the water quality is: m = ρ V =1.0×103kg/m3× 20×10-3m3 = 20kg.
The total mass of water and bucket is 20kg+4kg=24kg.
The total weight of water and bucket is: g total =m total g=24kg× 10N/kg =240N.
The human pulling force is: f ′ = (gTotal+gDynamic)/2 = (240n+15n)/2 =127.5n.
The speed of pulling movement is: v = 2v = 2× 0.2m/s = 0.4m/s.
The power of pulling force is: p = f ′ v =127.5n× 0.4m/s = 51w.
(20 10 Urumqi) has a solid cylindrical object. When weighing in air with a spring dynamometer, the reading of the dynamometer is10n; ; When half the volume of the object is immersed in water, the dynamometer reads 4N. Q:
(1) the volume of the object;
⑵ The buoyancy of the object when it is removed from the spring dynamometer and put into the water at rest.
Answer: solution: (1) F floating = G-F indication = 10N-4N = 6N.
F float =ρ×g××V
The solution is V= 1.2× 10-3m3.
⑵ = = 0.83×103 kg/m3.
Because the density of an object is less than that of water, it will float.
F float =G= 10N
1.(20 10. Liuzhou) This spring, a severe drought occurred in some parts of southwest China. A certain unit of the People's Liberation Army found water in a deep cave with a water depth of 4 meters. The officers and men used the device shown in Figure 20 to extract a bucket of water for sampling inspection. It is known that the volume of metal barrel is 2×l0-3m3. In the process of lifting the bucket rhyme at a constant speed, the pulling force of the bucket rhyme is l0 N, and after it is completely out of the water, the pulling force becomes 35 N (the friction between the rope and pulley and the weight of the rope are not juice, g = 10 N/㎏). Q:
(1) underwater pressure;
(2) the quality of the metal barrel;
(3) Metal density of the metal barrel.
Solution: (1) Pressure of bottom water: p = rhogh.
=1.0×103kg/m3×10n/kg× 4m = 4×104pa ...........................1min.
(2) mass of water in the barrel: m =ρ water v water.
=1.0×103kg/m3× 2×10-3kg = 2kg ...........................1min.
Gravity of water in the barrel: g water = mg = 2kg×10n/kg = 20n ..........................................1min.
Mass of barrel: m barrel = =1.5 kg ....................1min.
(3) Buoyancy of a bucket filled with water: f = F2-f1= 35n-10n = 25n.
Water in the bucket and the volume of the bucket: v = = 2.5×10-3m3 ...1min.
Metal volume: V metal =V-V water = 2.5×10-3m3-2×10-3m3 = 0.5×10-3m3 .....................................................1min.
Metal density: = 3×103kg/m3 ..........................1min.