|
||||||||||||||||
![]() ![]() |
||||||||||||||||
| | | | | | | | | | ||||||||||||
| | | | | | | | | | ||||||||||||
| | | | | | | | | | ||||||||||||
Units of measurement |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Units of measurement are the basic tools of physics and also some aspects of mathematics. Units of measurement that wiris allows us to represent include all of those in the International System of units (SI) and some others, such as the litre and the bar (atmospheric pressure), which have a practical relevance. It also allows users to define their own units with the command unit. In addition to the principal units, the SI system includes decimal multiples and submultiples, denoted using the prefixes deka,
hecto,
kilo,
deci,
centi,
milli... The complete list of units in the SI, along with their prefixes, names, abbreviations and the corresponding conversion factors with respect to basic units, can be found in the tables at the end of the chapter. The icons on the tab Units of measurement can be used to create units and measurements. For example, to express the metre, use the icon Some of the more common units we can use, from the SI or other systems, are: meter, gram, amper, kelvin, mol, liter, hour, minute, second, coulomb, henry, newton, joule, volt, ohm, hertz, pascal, bar, radian, siemens, farad, tesla, watt, weberYou will find the complete list of units included in wiris in the tables at the end of the chapter. Units can be multiplied and divided together to define new units. If a unit of measurement is multiplied by a number we obtain a quantity, which can represent the value of a measurement. Quantities corresponding to measurements of the same magnitude can be summed, multiplied or divided together even if not expressed in the same units. The units in which they are represented can be changed. To express a complex quantity in a single unit, use the command convert with the quantity as the first argument and the unit in which we wish the express the result as the second argument. Let's look at some examples:
Notation Physical quantities can be added, subtracted, multiplied and divided. In general, to add or subtract quantities we use the notation we refer to as complex. That is, we separate the quantities (remember that a quantity is a number followed by a unit) with spaces. wiris understands complex notation. Nonetheless, when in doubt it is advisable to use the usual symbols for addition and subtraction.
Arithmetic When adding and subtracting physical quantities, negative quantities can arise. When possible, wiris transforms these into the positive equivalent. Let’s look at some examples:
Functions The functions to convert quantities to different units are:
Basic units of the SI. Besides these, other units are defined:
Units derived from SI Defined from the basic units:
Units from other systems
Prefixes for the SI System of Units
The nomenclature in this chapter is based on the standard of the European Standards Committee. |
|
||
![]() |
powered by WIRIS
©2003 maths for more sl. All rights reserved. Legal notice |