Multiple units and unit transformation
As mentioned, SI-system informs basic units. For example, the basic unit for mass in one kilogram. However, this unit is exaggerated then talking about the mass of a spider. Furthermore, the measurements of a box are usually given in centimetres but volume in litres.
Prefix of a unit express its magnitude compared to a basic unit. For example,
If volume is solved with units of length but the context requires solution in litres, transformation can be done with
Let us study situation, where one metre is transformed to centimetres. As known, the result is 100 cm. If we use the previous table, the idea is to subtract power of end case from power of starting case. In our examples, the starting case is and the end case is . Thus,
The same idea is usable also with harder cases. See the examples below.
Examples 1:
Lengths:
Area:
Volume:
Example 2. Wind speed is informed to be 18 m/s. What speed of a car does it correspond?
Speed of a car is usually given as km/h. Let us transform the given wind speed to this unit:
Example 3. It is noticed, that there is dropping water from a pipe with a speed of 60 litres in two hours. Calculation need units in SI system, so let us transform it to m3/s.