physical quantity
Let an agent handle physical quantities with dimension, unit, value and uncertainty, as the parent of all measured quantities.
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 handle physical quantities with dimension, unit, value and uncertainty, as the parent of all measured quantities.
A property of a phenomenon, body or substance that can be expressed as a number and a unit, such as length, mass, time, temperature or energy.
What it is for: The basis for measurement and quantitative science.
It can be measure it; express it with units; check dimensions; use it in equations.
Distinguishing features
Numerical value times unit
Has a dimension
Scalar, vector or tensor
Base and derived quantities in ISQ
What it looks like
Numbers with units.
How it is recognised
Value with unit
Quantity symbols such as m, t, T
Specific quantities are separate entries
Related models
has kind - kinds
is measured in - units
is determined by - process
is defined in - system
In practice
Families and kinds
base quantities: length, mass, time, current, temperature, amount, luminous intensity
derived quantities
scalar and vector quantities
dimensionless quantities
Identifiers
ISO 80000 quantity part and item number definitions
Standards and regulation
ISO 80000 Quantities and units
SI Brochure
Failure modes and hazards
Missing units
Dimension errors
Ignoring uncertainty
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 Which quantity.
Definitions from ISQ.
Quantity
Name and symbol.
Quantity
Quantity identity.
- Which physical quantity is meant? definition
- What is its dimension? definition
Type
Scalar or vector.
Type
Quantity type.
- Is it scalar, vector or tensor? definition
- Is it dimensionless? definition
Measurement Value and unit.
Values need units and uncertainty.
Value
Number and unit.
Value
Value.
- What is the value and unit? measurement
- What is the uncertainty? measurement
Method
How measured.
Method
Method.
- How was it measured? provenance
- Is it traceable? provenance
Relations Equations.
Quantities relate in laws.
Laws
Equations.
Laws
Relations.
- Which laws relate it to other quantities? definition
- Are dimensions consistent? boundary
Derived
From base quantities.
Derived
Derivation.
- How is it derived from base quantities? definition
- What is its SI unit? definition
Communication Reporting.
Reports must be complete.
Reporting
Value, unit, uncertainty.
Reporting
Reporting.
- Is it reported with unit and uncertainty? boundary
- From which source? provenance
Specific entry
Children.
Specific
More specific entry.
- Which specific quantity entry fits? action
- Is it listed? provenance
What the second pass must settle
- How should the registry organise physical quantities?
- How should ISO 80000 items be linked?
- How should scalar and vector types be recorded?