In physics, the relationship between density, mass, volume, and pressure

In physics, the relationship between density, mass, volume, and pressure

1. Density, mass, volume - ρ = m / V
The same kind of material has a certain density, and its mass is proportional to its volume
Different substances have a certain mass, and the density is inversely proportional to the volume
Different substances have a certain volume, and the density is directly proportional to the mass
2. Pressure, pressure, contact area -- P = f / S
The pressure is constant, and the pressure is proportional to the contact area
When the pressure is constant, the pressure is inversely proportional to the contact area
The pressure is proportional to the area