scalar quantity
Let an agent distinguish scalar quantities from vectors and tensors, and handle them with units and values.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent distinguish scalar quantities from vectors and tensors, and handle them with units and values.
A physical quantity described by magnitude alone, without direction, such as mass, temperature, energy, speed or electric charge density.
What it is for: Describing magnitudes in physics and engineering.
It can be measure and compute it; add and compare values; convert units; combine with vectors in formulas.
Distinguishing features
Magnitude only
Unaffected by rotation of coordinates
Contrasts with vectors such as force
Some quantities are pseudoscalars
What it looks like
A number with a unit.
How it is recognised
Values with units and no direction
Symbols without vector arrows
Examples such as angular speed or luminous exitance
Related models
is a kind of - category
is confused with - direction
has kind - examples
is measured in - units
In practice
Families and kinds
mechanical scalars: mass, energy, speed
thermal scalars: temperature
electrical scalars: charge, potential
photometric scalars: luminous exitance
Standards and regulation
ISO 80000 quantities and units
SI Brochure
Failure modes and hazards
Treating vectors as scalars
Unit errors
Also called
+36
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Definition What it is.
Scalars have magnitude only.
Quantity
Which quantity.
Quantity
The quantity.
- Which scalar quantity is this? definition
- What is its SI unit? definition
Nature
Scalar or not.
Nature
Scalar status.
- Is it truly scalar, or a component of a vector? boundary
- Is it a pseudoscalar? boundary
Measurement How measured.
Measurements need methods.
Method
Instruments.
Method
Method.
- How is it measured? provenance
- With what uncertainty? measurement
Units
Conversion.
Units
Units.
- In which unit is it given? definition
- How does it convert? measurement
Use In calculations.
Scalars combine with other quantities.
Operations
Arithmetic.
Operations
Valid operations.
- Which operations are valid with this quantity? definition
- Can it be added to others? boundary
Formulas
With vectors.
Formulas
Role in formulas.
- How does it appear in formulas with vectors? definition
- Is the dimension consistent? boundary
Communication Clear values.
Values must be clear.
Reporting
Value and unit.
Reporting
Reporting.
- Is the value reported with unit and uncertainty? boundary
- From which source? provenance
Education
Explaining.
Explanation
Explanation.
- How can the scalar-vector difference be explained? action
- What example helps? action
What the second pass must settle
- Should scalar status be a property of quantity entries?
- How should pseudoscalars be treated?
- The registry entry has merged aliases such as magnetomotive force; should they be linked as instances?