## Summary:

- Some units are combinations of SI base units.
- A derived unit is a unit that results from a mathematical combination of SI Base units.
- We have already discussed volume and energy as two examples of derived units.
- Some others are listed in the Table below:Area, force, speed, density, energy, volume, mass, mass-to-weight ratio, mass to weight ratio, volume to mass, energy to mass.
- Using dimensional analysis with derived units requires special care.
- When units are squared or cubed as with area or volume, the conversion factors must also be squared.

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