body
an individual 3-dimensional object that has mass and that is distinguishable from other objects
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.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise an individual physical body, assess its spatial and mechanical state, and judge whether a proposed physical interaction is feasible.
A physical body is an individual material object with mass and three-dimensional spatial extent that can be distinguished from other objects by a physical boundary or an explicitly defined system boundary.
It can be Locate and track the body using its extent, boundary and observation history.; Measure its mass, geometry and motion with declared methods and uncertainty.; Assess whether it fits through an opening or within a containing region.; Assess support, balance and movement under stated contact and loading conditions.; Plan translation, rotation or restraint when the relevant mechanical properties are known.; Recognise material loss, deformation or separation and reconsider which resulting objects retain the original identity..
Distinguishing features
The referent is an individual physical object with mass and three-dimensional extent, rather than a shape or mathematical region alone.
A stated boundary criterion distinguishes its matter from neighbouring bodies and its surroundings; a name or arbitrary spatial selection alone does not establish this.
The referent is this particular body, rather than the substance it consists of or the class of objects to which it belongs.
Contact with another body does not by itself establish that the two are one body; cohesion, attachment and the chosen individuation criterion must be examined.
The word body denotes a physical object here; anatomical, organisational and textual senses require neighbouring models.
Scope
+ Individuation of a physical body and its separation from surrounding matter
+ Three-dimensional extent, occupied volume, surfaces and internal voids
+ Mass, mass distribution and resistance to changes in motion
+ Position, orientation, motion and deformation in a stated reference frame
+ Physical continuity through contact, material exchange, fragmentation and assembly
+ Mechanical conditions relevant to supporting, moving or containing the body
- The anatomical or physiological sense of body and organism-specific life processes
- An organisation, committee or collective described as a body
- A material or substance considered independently of any individual portion
- Device functions, operating procedures and product classifications
- Legal ownership, economic value and administrative asset identity
- Abstract geometrical solids, point particles and fields considered without an individual massive three-dimensional object
Characteristics
- Individuation criterion
- Observed surface, material interface, cohesive continuity, connected assembly or unresolved Establishes which matter is treated as one body and makes ambiguous boundaries explicit.
- Constituent and surrounding matter
- Links to constituent materials, component bodies, enclosing bodies and surrounding media Separates the body from its composition, parts and environment.
- Mass
- kg, with measurement time, method and uncertainty Supports mechanical assessment and distinguishes mass from a force measured as weight.
- Spatial extent
- Dimensions in m and volume in m³; distinguish external envelope, material volume and void volume Determines fit and clearance while avoiding incompatible meanings of volume.
- Centre of mass
- Coordinates in m relative to a stated body or external frame Helps assess balance, support and response to applied forces.
- Rotational inertia
- kg·m² about a specified axis, or an inertia tensor with stated origin and frame Describes rotational response that mass alone cannot determine.
- Position and orientation
- Position in m and orientation using a declared convention, reference frame and time Locates the body's extent and enables meaningful comparison between observations.
- Motion
- Linear velocity in m/s and angular velocity in rad/s, with reference frame and time Supports prediction of displacement and contact.
- Deformation regime
- Rigid approximation adequate, deformable response required or unresolved for the stated task Determines whether fixed geometry can support the intended decision.
- Support and contact configuration
- Contact regions, supporting bodies, attachments and permitted relative movements Constrains motion and identifies how loads pass between bodies.
- Physical integrity
- Observed continuity, cracks, separations, missing matter and residual deformation Records changes that may affect both mechanical behaviour and continued identity.
Analytical facets
- substance
- material
- origin
- natural
- agency
- inert
- mobility
- varies
- scale
- not-applicable
- affordances
- observable
Also called
+80
Where this came from
oewn:2024 · CC BY 4.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 5 bundles · 9 layers · 13 findings · 21 questions.
Individuation and continuity Establish what counts as this body and when a physical change challenges that identification.
Being distinguishable from other objects is part of the registry definition and requires more than assigning an identifier.
Boundary of matter
Identify the physical evidence separating the body's matter from its surroundings.
Basis for one body
Record whether surfaces, interfaces, cohesion or connections support treating the referent as one individual body.
- What observable boundary or continuity criterion makes this one body rather than an arbitrary region or collection? definition
- Which contacting, attached or enclosed matter is included, and which belongs to another body? boundary
Persistence through change
Track identity when matter or connections change.
Identity-changing events
Record material exchange, fragmentation and joining without assuming that physical continuity always preserves one identity.
- What observations connect the present body to its earlier physical state? provenance
- After material loss, fragmentation or joining, which identity decision remains justified by the stated individuation criterion? boundary
Three-dimensional occupation Describe the space occupied by the body and how that description changes with pose.
A body has physical extent; its location alone cannot establish fit, separation or contact.
Surface, envelope and voids
Distinguish actual material extent from a simplified enclosing shape.
Meaning of measured volume
Record dimensions and volume with explicit treatment of cavities, pores and geometric approximations.
- What dimensions and volume have been measured, and at what spatial resolution and uncertainty? measurement
- Does the reported volume describe material, displaced volume or an external envelope, and how are voids treated? boundary
Pose and clearance
Relate body geometry to a reference frame and nearby physical boundaries.
Occupied and swept space
Use pose and geometry to assess present occupation and the space needed for a proposed movement.
- What reference frame, origin, orientation convention and time locate the body's geometry? measurement
- Does the proposed translation or rotation maintain sufficient clearance throughout its path, allowing for geometric uncertainty and deformation? action
Mass and inertial response Represent how much mass the body has and how its distribution affects motion.
Mass is constitutive of this registry sense, while its distribution determines balance and rotational response.
Mass assessment
Establish total mass for a clearly delimited body at a stated time.
Mass measurement basis
Separate a mass estimate from instrument force readings, included contents and inferred values.
- What is the body's mass in kilograms, and what method, time and uncertainty accompany the value? measurement
- Which components or contents were included, and what corrections or assumptions were used if mass was inferred from weight or density? provenance
Distribution of mass
Describe mass placement at the level needed to assess balance and rotation.
Centre and rotational inertia
Record the centre of mass and relevant rotational inertia without assuming uniform density.
- Where is the centre of mass in the stated configuration, and how was it established? measurement
- What rotational inertia about the proposed axis is known, and could moving contents or deformation change it? measurement
Mechanical state and interaction Describe motion, constraints and physical response relevant to acting on this body.
A massive extended body responds to forces through motion, deformation or separation, depending on its configuration and condition.
Motion and constraints
Establish current motion and the contacts or attachments that restrict it.
Supported and permitted motion
Record observed velocities and support conditions before predicting the effect of a physical action.
- What linear and angular motion is observed relative to which frame and over what interval? measurement
- Which contacts and attachments constrain the body, and what motion becomes possible if a support is moved or removed? action
Deformation and integrity
Determine whether shape and continuity can be treated as stable under the proposed interaction.
Adequacy of rigid-body treatment
Make the rigid-body approximation conditional on the task, observed condition and expected loading.
- What observed deformation, cracking or separation limits treating the body as having fixed geometry? measurement
- What evidence supports the proposed load or restraint, and which deformation or failure limits remain unknown? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This entry covers the general physical-object sense of body, not an anatomical body or an organisation.
- Rigid and deformable describe modelling treatments; perfect rigidity is an idealization.
- Boundaries and continued identity can require explicit conventions for fluid bodies, aggregates and objects exchanging matter; no universal identifier scheme, regulatory regime or typical size applies.
- Which of these check these first hold for the sense of body this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Solid body
- Fluid body
- Composite body
- Rigid body (idealization neglecting deformation)
- Deformable body
- Which of these kinds and varieties hold for the sense of body this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Defining the object whose forces and motion are analysed in mechanics.
- Calculating balance and stability using mass distribution and centre of mass.
- Modelling deformation, stress and strain under applied loads.
- Tracking collisions and exchanges of momentum and energy.
- Defining a material system for thermal analysis.
- Which of these real-world use hold for the sense of body this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Mass - Positive; no typical range applies across all physical bodies. - kg
- Volume - Positive; depends on the object's scale and the boundary used. - m³
- Mean mass density - Mass divided by the specified volume; no universal typical range. - kg/m³
- Moment of inertia about a specified axis - Depends on mass distribution and the chosen axis; no universal typical range. - kg·m²
- Which of these typical measurements hold for the sense of body this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Human or animal body - An organism's anatomical body is a particular biological case; this sense includes nonliving material objects.
- Material - A material is what an object consists of; a body is an individual object constituted from material.
- Point particle - A point-particle model neglects spatial extent; a body has three-dimensional extent even when approximated as a point.
- Physical system - A physical system can include multiple bodies, fields and their interactions; it need not be one individual material object.
- Geometric solid - A geometric solid is an abstract spatial figure and need not possess mass or material constitution.
- Device - A device has an intended function; a physical body need not be designed or serve any purpose.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of body this model covers, and on what evidence? provenance
What the second pass must settle
- Does an existing Vercy world model already own this physical-object concept, requiring this registry entry to link to it?
- Which individuation criteria should determine whether loose aggregates, connected assemblies and contained fluids count as one body?
- How should body identity persist through erosion, replacement of matter, fragmentation and fusion?
- What scale and boundary resolution should apply when surfaces are porous, diffuse or changing?
- Which mechanical properties belong in this general body model, and which should be supplied by material, organism or device models for a particular action?