Density

Definition

Density ( $\rho$ ) is the measure of mass per unit of volume: $\rho = m/V$ .

It determines whether objects float or sink, and is a fundamental property of materials.

Density ( $\rho$ ):
$\rho = \frac{m}{V}$ (Mass / Volume)
How to read: “The density rho is equal to the mass m divided by the volume V.”
Meaning: Mass per unit volume—how tightly packed matter is.
Unit: Pascal (Pa). $1 \text{ Pa} = 1 \text{ N/m}^2$ .
How to read: “One pascal is equal to one newton per square meter.”
Pressure in a Liquid: Depends on depth and weight density. It is exerted equally in all directions.
Boyle’s Law: For a fixed amount of gas at constant temperature, pressure and volume are inversely proportional.
$P_1 V_1 = P_2 V_2$
How to read: “The initial pressure times the initial volume is equal to the final pressure times the final volume.”
Meaning: Boyle’s law—at fixed temperature, pressure and volume are inversely proportional.