浮力知识点归纳总结英文知识
1.Pressure:The force acting vertically on the surface of an object is called pressure.
2.Pressure:The pressure on the unit area of an object is called pressure.
3.Pressure formula:P=F/S,where the unit of p is Pascal,abbreviated as Pa,1 Pa=1 N/m2,and the unit of pressure F is N;Force bearing area S unit:m2
4.Pressure increasing method:(1)S remains unchanged,F↑;(2)F remains unchanged,S↓(3)Set F↑,S↓at the same time.The pressure reduction method is the opposite.
5.The reason for the liquid pressure is that the liquid is subject to gravity.
submarine6.The characteristics of liquid pressure:(1)liquid has pressure on the bottom and wall of the container,(2)liquid has pressure in all directions;(3)The pressure of liquid increases with the depth.At the same depth,the pressure of liquid in all directions is equal;(4)The pressure of different liquids is also related to the density.
7.*Calculation formula of liquid pressure:（ρIs the liquid density,in kg/m3;G=9.8 N/kg;H is the depth,which is the vertical distance from the liquid free surface to a point inside the liquid,in meters.)
8.According to the liquid pressure formula:it can be obtained that the pressure of the liquid is related to the density and depth of the liquid,but not to the volume and mass of the liquid.
9.The experiment proving the existence of atmospheric pressure is the Madelberg Hemisphere Experiment.
10.The cause of atmospheric pressure:the air is produced by gravity,and the atmospheric pressure decreases with the increase of height.
11.The experiment to determine the atmospheric pressure is the Torricelli experiment.
12.The instrument for measuring atmospheric pressure is:barometer.Common barometers include mercury barometer and aneroid barometer(metal box barometer).
13.Standard atmospheric pressure:equal to 760 mm of mercury.1 Standard atmospheric pressure=760 mm Hg=1.013×105 Pa=10.34 m water column.
14.The relationship between boiling point and pressure:the boiling point of all liquids decreases when the pressure decreases,and increases when the pressure increases.
15.The relationship between fluid pressure and flow velocity:the higher the flow velocity,the lower the pressure;The lower the velocity,the higher the pressure.
1.Buoyancy:All objects immersed in liquid are subject to the vertical upward force of the liquid.This force is called buoyancy.The direction of buoyancy is always vertical upwards.(Objects are also buoyant in the air)
2.Conditions of object sinking and floating:(initially immersed in liquid)
Method 1:(specific buoyancy and object gravity)
(1)F floats G,floats up(3)F floats=G,floats or floats
Method 2:(Specific density of object and liquid)
(1)F floats G,floats up(3)F floats=G,floats.(Will not float)
3.The cause of buoyancy:the object immersed in the liquid is subject to the upward and downward pressure difference of the liquid.
4.Archimedes principle:an object immersed in a liquid is subject to upward buoyancy,which is equal to the gravity of the liquid it displaces.(The buoyancy of an object immersed in gas is equal to the gravity of its expelled gas)
5.Archimedes principle formula:
6.The buoyancy calculation methods include:
(1)Weighing method:F floating=G-F,(G is the weight of the object,and F is the reading of the spring scale when the object is immersed in the liquid)
(2)Pressure difference method:F floating=F upward-F downward
(3)Archimedes principle:
(4)Balance method:F floating=G object(suitable for floating and suspension)
7.Buoyancy utilization
(1)Ship:hollow material with density greater than water,so that it can discharge more water.This is why ships are made.
(2)Submarine:sink and float by changing its gravity.
(3)Balloon and airship:A gas filled with less density than air.

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