Quantities and Units

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Quantities and Units

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In 20-sim, to every constant, parameter and variable a quantity may be assigned. Well known quantities are for example position, velocity, time and energy. 20-sim will use these quantities to check the validity of (basic) equations. The value of a quantity can be expressed in a specific unit. The quantity time can for example be expressed in the unit second or in the unit minute:

 

quantity

unit

multiplication to SI unit

 

Time

second (SI unit)

minute

hour

day

1

60

3600

31556926.08

 

Position

meter (SI unit)

foot

inch

yard

1

0.3048

0.0254

0.9144

 

In 20-sim a quantity can be expressed in every desired unit. To prevent conversion problems, internal calculations are always performed in standard SI-units. Therefore non-SI units are stored with a multiplication factor. When a variable has a unit, the unit can also have common engineering prefixes. For example, a parameter m {kg} with a value of 0.1 can be selected in the Parameters / Initial Values Editor. If you click on the unit, you can select other units to enter the mass.

UnitsParametersEditor

You can use the units in the Parameters / Initial Values Editor to select a desired unit.

You can enter new quantities and units in the Domains, Quantities and Units Editor.