Units are used to measure and describe quantitative data. A unit of measured is a definite magnitude of a physical quantity defined and adopted by convention or by law that is used as a standard for measurement of the same physical quantity. Any other value of that physical quantity can be expressed as a simple multiple of the unit of measurement.
Utilizing and converting units allows scientists and mathematicians to manipulate data by using ratios. There are two main systems of units. International System of Units, S.I units and Engineering Engineering Units, E.E. Units. S.I. units are the modern form of the metric system. It is comprised of seven bases units. This system is international accepted. Only Burma, Liberia and the United States have not adopted this system of units. E.E. units are another system of units used. This system has inconsistencies in converting and requires different conversion factors.
For example, length is a physical quantity. The metre is a unit of length that represents a definite predetermined length. When we say 10 metres, we actually mean 10 times the definite predetermined length called “metre”.
|Dimension||EE Units||SI Units|
|Time||Second (sec)||Second (s)|
|Length||Foot (Ft)||Metre (m)|
|Mass||Pound mass (Lbm)||Kilogram (Kg)|
|Force||Pound Force (Lbf)||Newton (N)|