Mass · Volume · Density
How much mass occupies a given volume? Compare two objects in 3D.
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Left: reference
Mass m2 kg
Volume V1 dm³
Density ρ2 kg/dm³
Right: your object
Mass m2 kg
Volume V1 dm³
Density ρ2 kg/dm³
ρ = m / V = 2 kg / 1 dm³ = 2 kg/dm³
This equals 2 000 kg/m³.
V = a × b × c = 1 dm × 1 dm × 1 dm = 1 dm³
Initial example: both objects have the same mass, volume and density.
Helium: approximate density ρ ≈ 0.164 kg/m³ at about 25 °C and 1 atm. An ideal massless envelope is assumed; the rise is schematic. During filling, helium mass increases but remains much smaller than the reference mass. If the same sealed quantity of gas expands, its mass stays constant.
Mass m is measured in kilograms; volume is the space occupied by an object; density is mass per unit volume. 1 dm³ = 1 litre = 0.001 m³. Each gold marker symbolically represents 0.25 kg. Each purple helium marker represents 0.25 g, a mass scale 1 000 times smaller. These are not individual molecules. A partially filled marker represents the corresponding fraction of mass. The general objects are calculation examples. The helium animation uses an approximate density for the real gas.