(1) p = f/S. This is the definition of pressure, which is applicable to the pressure generated by solids, liquids and gases, and is generally used to calculate the pressure generated by solids. The pressure formula can be obtained by mathematical deformation of this formula: F=PS.

(2) p = f/s = g/s = mg/s = rhovg/s = rhoshg/s = rhogh (for liquids). This formula is derived from P=F/S and is often used to calculate the pressure inside a liquid.

Second, the density formula:

ρ=m/V

This formula obtains the density of the object, not necessarily the density of the object material. When an object is solid, the density of the object and the density of the material are equal.

Extended data

Application of density

1, identify the materials that make up the object.

Density is one of the characteristics of matter. Every substance has a certain density, and the density of different substances is generally different. So we can use density to identify substances. The method is to measure the density of the measured substance, and compare the measured density with the density of various substances in the density table, so as to identify what substances the object is made of.

2. Calculate the composition of various substances contained in an object.

3. Calculate the mass of an object that is difficult to weigh or the volume of an object with complex shape.

According to the change of density formula: m=Vρ or V=m/ρ, we can calculate the mass and volume of objects, especially some problems that are inconvenient for direct measurement, such as calculating the volume of irregular objects and the quality of historical sites.

4. Calculate the internal pressure and buoyancy of the liquid. (Density can also be used to calculate cylinder pressure.)

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