density

What is density?

The mass per unit volume of a substance.

State the equation for density.

Density = mass ÷ volume (ρ = m / V).

What are the units of density?

kg/m³.

What does it mean if a material has a high density?

It has a lot of mass packed into a small volume.

What does it mean if a material has a low density?

It has little mass in a given volume.

How do you find the density of a regular solid?

Measure mass with a balance; calculate volume using length × width × height; use ρ = m / V.

How do you find the density of an irregular solid?

Measure mass; find volume using water displacement; use ρ = m / V.

How do you find the density of a liquid?

Measure mass of empty container; add liquid and measure again; calculate mass of liquid; measure volume; use ρ = m / V.

Why do gases have low density?

Their particles are far apart.

Why do solids usually have high density?

Their particles are packed closely together.

Why does a substance float in water?

Its density is less than the density of water.

Why does a substance sink in water?

Its density is greater than the density of water.

What happens to density when a substance is compressed?

Density increases because particles are forced closer together.

What happens to density when a substance expands?

Density decreases because particles move further apart.