Density · revision map · IGCSE 0625, Topic 1.4
TOPIC 1.4 · DENSITY
CAMBRIDGE IGCSE PHYSICS 0625 · ONE-PAGE REVISION MAP
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DENSITY1.4
What is Density
Density is the mass packed into each unit of volume.
ρ = m / V
ρ = density
m = mass
V = volume
m = mass
V = volume
- Units: kg/m³ or g/cm³.
- Water has a density of 1000 kg/m³.
Regular Solids
Find the mass on a balance and the volume from the measured dimensions.
V = l × w × hThen use ρ = m / V.
Irregular Solids & Liquids
Find an awkward volume by displacement.
- Lower the solid into a full can; the water that overflows has the same volume as the solid.
- For a liquid, measure its mass, then read its volume in a measuring cylinder.
Floating & Sinking
An object floats if it is less dense than the fluid, and sinks if it is denser.
- Ships float: their average density is low.
- A hot air balloon rises as the warm air inside is less dense than the cool air outside.