"Integration of this Chapter" Buoyancy PPT

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"Integration of this Chapter" Buoyancy PPT

High School Entrance Examination Focus Experience

1. (2018·Shandong Linyi High School Entrance Examination) On April 20, 2018, my country's most advanced autonomous submersible "Qianlong 3" (shown in the picture) successfully made its first dive. When the submersible dives at a constant speed under the water surface (not counting the resistance of the water) ()

A. The gravity experienced is less than the buoyancy force

B. The pressure difference between the upper and lower surfaces becomes larger.

C. The pressure increases and the buoyancy increases.

D. The pressure increases and the buoyancy remains unchanged.

Analysis: The submersible dives at a constant speed under the water surface. At this time, the density of the water remains unchanged. When the submersible is immersed in the water, the volume of water it displaces remains unchanged, but the depth in the water gradually increases. According to the formula p = ρgh and the formula F float = ρ liquid gV discharge, it can be seen that the pressure on the submersible increases and the buoyancy remains unchanged, that is, the pressure difference between the upper and lower surfaces remains unchanged. Therefore, options A, B, and C are all incorrect, and D is correct.

2. (2018·Chongqing High School Entrance Examination Paper B) A thin-walled cylindrical container on a horizontal table contains a certain liquid. The bottom area of ​​the container is 80 cm2. A metal ball with a volume of 100 cm3 is tied with a thin wire and sinks to the bottom of the container. At this time, the depth of the liquid is 10 cm, and the pressure of the metal ball on the bottom of the container is 1.9 N, as shown in the figure. Now take the metal ball out of the liquid. The pressure of the liquid on the bottom of the container changes by 100 Pa. When the metal ball is taken out of the container, the volume of the liquid and the thin wire on the surface is not counted. Then the following judgment is correct (g is 10 N/kg) ()

A. The buoyancy force on the metal ball in the liquid is 1 N

B. The gravity of the liquid in the container is 6.4 N

C. After taking out the metal ball, the pressure of the container on the tabletop is reduced by 100 Pa.

D. The density of the metal ball is 2.7×103 kg/m3

3. (2017·Shandong Linyi High School Entrance Examination) Hang two objects under a spring dynamometer respectively and let them be immersed in water at the same time. If the decrease value of the two spring dynamometers is the same, then the two objects must have the same ()

A.Density B.Volume

C. Mass D. Gravity

Analysis When two objects are immersed in water at the same time, the decrease value of the two spring dynamometers is the same, indicating that the buoyancy force on the two objects is the same. According to Archimedes' principle, the volumes of liquid displaced by the two objects are the same. These two objects The objects must have the same volume.

4. (2017·Hunan Yiyang High School Entrance Examination) As shown in the figure, a cuboid object is immersed in a container filled with sufficiently deep water and is in a suspended state. The pressure on its upper surface is 1.8 N, and the pressure on its lower surface is 3 N, then the buoyancy force on the object is ________N; if the object sinks another 5 cm, the buoyancy force on it is __________N.

5. (2016·Sichuan Neijiang High School Entrance Examination) Many ships have displacement marks. The displacement of the "Qingdao" guided missile destroyer when fully loaded is 4,800 t, which means that the mass of seawater displaced by it floating on the sea is 4,800 t. At this time The buoyancy force on the ship is ________N (g is 10 N/kg). When the ship sails from the ocean into the Yangtze River, the draft is _________ (optional "get bigger", "get smaller" or "unchanged").

Analysis (1) The destroyer floats, and the buoyancy force it experiences is F float = G ship = m row g = 4.8 × 106 kg × 10 N/kg = 4.8 × 107 N. (2) When a destroyer travels in the Yangtze River, the buoyancy force is equal to gravity. According to Archimedes' principle, since the density of the liquid becomes smaller, the volume of displaced water increases, and the draft of the ship becomes larger.

Answer 4.8×107 becomes larger

6. (2017·Zhejiang Jinhua High School Entrance Examination) The "Colorful Ball Thermometer" is a modern home accessory. Its structural model is as shown in the figure. The "Colorful Ball Thermometer" is composed of small balls with the same volume (keep constant) and different masses. A liquid composition whose density decreases with increasing temperature. When the ambient temperature rises, the buoyancy force on the ball immersed in the liquid will be ______. At a certain ambient temperature, the four balls are in the position shown in the figure. At this time, the buoyancy force on ball B is the same as the buoyancy force on ball D. The relationship between the size of the buoyancy force is ______.

Keywords: Free download of PPT courseware for eighth-grade physics volume 2 of the People's Education Press, integrated PPT download for this chapter, buoyancy PPT download, .PPT format;

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Update Time: 2024-10-05

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 2 industry PPT template

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