- Part 1 – SI Base units
- Part 2 – Derived units
- Part 3 – Secondary units and prefixes
- Part 4 – Units outside the SI
- Part 5 – Using SI units and their symbols
- Part 6 – Some useful physical constants
Certain units are not part of the SI, but are so widely used that they are generally accepted within scientific writing.
A few of the units in this category are shown in Table 4.
Table 4 Units accepted for use with the SI
|Time||minute||min (not mins)||1 min = 60 s|
|Time||hour||h||1 h = 3600 s|
|Time||day||d||1 d = 86,400 s|
|Temperature||degree celsius||°C||°C = K-273.15|
|Mass||tonne||t is often used||1 tonne = 103 kg|
Note that so-called ‘imperial units’ (e.g. inch, foot, yard, gallon) are no longer acceptable in scientific writings or reports although you might still come across such units in ‘everyday life’. See Appendix 1 for more examples of common units and their SI equivalents.