Density and Pressure

Density

Density is a measure of how compact a substance is or the amount of mass per unit volume.
It can be calculated using the formula density = mass / volume.
If an object is denser than the fluid it is placed in, it will sink. If it is less dense, it will float.
The unit of density is kg/m³ in the SI system.
When a force acts on an object, it can produce a change in shape. This change in shape can lead to a change in volume, thus a change in density.
The density of a material doesn’t depend on the quantity or the shape of the material. It is a property solely of the material itself.

Pressure is the effect of a force acting over a certain area.
The formula for calculating pressure is pressure = force / area.
Pressure is measured in units called pascals (Pa). One pascal is equivalent to one newton per square meter.
In a fluid (which includes both liquids and gases), pressure increases with depth due to the weight of the fluid above. This is why pressure increases the deeper you go into a body of water.
Atmospheric pressure decreases with increasing altitude or height.
In terms of gases, if the volume is constant (as in a sealed container), increasing the temperature of the gas will lead to an increase in pressure. This is due to gas particles moving more with increased temperature and hitting the walls of the container more frequently and with more force.
For a given gas at a constant temperature, the product of pressure and volume is a constant. This is known as Boyle’s law.
Pressure differences are what cause fluid flow. Fluids always flow from areas of higher pressure to areas of lower pressure.