Practice

ρ = m/V Formula – How to Calculate Density (Practice)

ρ = m/V — Mass density

Density is mass per unit volume: ρ = m/V. Materials with higher ρ pack more mass into the same space. Convert cm³ and grams carefully — 1 g/cm³ = 1000 kg/m³.

Guide — how to use this formula

1. 1. Use SI: kg and m³ for kg/m³ answers.
2. 2. Or compute g/cm³ then × 1000 for kg/m³.
3. 3. Rearrange: m = ρV, V = m/ρ.
4. 4. For mixtures without gaps: ρ = (Σm)/(ΣV).

Derivation

Density is defined as mass divided by volume:

1. Definition:
   \rho = \frac{m}{V}
2. Weight of a uniform sample near Earth:
   W = mg = \rho V g

Don’t invert the ratio — density is m/V, not V/m.

Examples

Example: 10 kg in 2 m³

ρ = 5 kg/m³.

Example: g/cm³

2 g/cm³ = 2000 kg/m³.

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