Density: mass packed into space

4 minAS Level4.3.1

By the end of this lesson

By the end, you can define density as mass per unit volume and use the definition to find density, mass or volume.

Definition

Density

Density is the mass per unit volume of a substance. Its symbol is the Greek letter rho, written $\rho$ .

Same space, different amount of matter

Picture two equal-sized boxes. If one contains more mass, its contents are more densely packed: its density is greater.

$\rho = \dfrac{m}{V}$

Here $m$ is mass and $V$ is volume. In SI units, use kilograms for mass and cubic metres for volume, giving density in $\text{kg m}^{-3}$ .

Quick check

Multiple choiceQuestion 1 · Recall

CalculateQuestion 2 · Recall

Answer the 2 questions above to continue.