In 245 B.C., Archimedes discovered the principle of buoyancy. Definition of buoyancy for the F float = G row (that is, the buoyant force on the object is equal to the object sinking at rest after the displacement of the liquid gravity), the calculation can be used to derive the formula F float = ρ liquid gV row (ρ liquid that the density of the liquid, the unit of kilograms / cubic meters; g represents a constant, is the ratio of the force of gravity to the mass of the value of g = 9.8N / kg in the rough calculations can be taken as 10N / kg; V row of the volume of the liquid, the unit is a cubic meter). (the unit is cubic meter). Also, the buoyancy formula for liquids applies to gases.
The cause of buoyancy: the object immersed in the liquid or gas is subjected to the difference between the upward and downward pressure of the liquid or gas on the object.
The pressure on the lower surface of an object in a liquid is greater than the pressure on the upper surface of the object in the liquid, so the combined force is F up - F down, because there is pressure in all directions inside the liquid, so the upper surface of the object is under a downward pressure from the liquid, and the lower surface of the object is under an upward pressure from the liquid. Since in the same liquid, the greater the depth, the greater the pressure, the pressure on the lower surface of the object is obviously greater than the pressure on the upper surface of the object, so it is F up - F down.
Cause
The upper and lower surfaces of the object are in different depths of the liquid (or gas), the pressure of the liquid (or gas) is not the same, the lower surface of the upward pressure is greater than the upper surface of the downward pressure, the difference between the two pressures form the buoyant force. The size of the buoyant force is closely related to the amount of liquid (or gas) the object discharged.
To the object immersed in liquid, for example, because the liquid will produce pressure, and pressure increases with the depth and become larger, and the liquid inside the pressure in all directions, so the object under the bottom surface of the liquid upward pressure is larger, on the bottom surface of the liquid by the downward pressure is smaller, the object on the bottom of the pressure difference between the upper and lower surfaces of the vertical buoyancy that is manifested upward. The pressure on the sides cancel each other out.
Factors
Buoyancy is related to the volume of the object immersed in the liquid and the density of the liquid. It is independent of the depth of the object in the liquid, the shape of the object, its mass, its density, and its state of motion.