- The sl unit for density is kilogram per cubic metre ( kg m-3 ).
- Another commonly used unit for density is gram per cubic centimeter ( g m-3 ).
- Densities of common substances:
- When an object is placed in a liquid of lower density, the object sinks. When it is placed in a liquid if a greater density, it floats.
- For example, a copper sphere of density 8.9 g cm-3 sinks in water of density 1.0 g cm-3 but floats in mercury if density 13.6 g cm-3. The denser the liquid, the higher an object will float in the liquid.
- The hydrometer is used to meausre the density of a liquid.
- The hydrometer is specially designated to float in a liquid and to measure its density.
- If the hydrometer "floats higher", it indicated that the liquid has a higher density.
- Special hydrometers are used to test whether a car battery is fully charged or whether milk has been diluted with water.
- Example of a hydrometer:
