{ "model": { "rank": 5956, "code": "thing-q2945123", "model_id": "vr.tr.center-of-mass", "name": "center of mass", "purpose": "Let an agent explain the centre of mass and its relatives, relay definitions, calculation and applications from mechanics references, describe centroids, barycentres and centres of buoyancy, and distinguish centre of mass from centre of gravity in non-uniform fields, from the centroid of a shape and from the centre of pressure.", "family": "Thing Registry", "category": "Cross-cutting context", "status": "research-draft", "kind": "thing", "plane": "XCT", "domain": "XCT.QLT", "industry": "", "version": "", "url": "/models/thing/q2945123/", "tier": 2, "score": 63, "payload": { "layer": "wikidata", "aliases": [ "center of gravity", "centroid", "barycenter", "centers of gravity in non-uniform fields", "triangle centroid", "centre of buoyancy", "center of gravity of the surface", "Spieker center" ], "aliasCount": 8, "merged": 8, "knownIn": 63, "facets": null, "markers": [], "lexicalClass": "", "senseRank": null, "alsoRegisteredAs": null, "source": { "dataset": "wikidata", "item": "Q2945123", "url": "https://www.wikidata.org/wiki/Q2945123", "license": "CC0 1.0" } }, "research": { "vercy": "1.0-draft", "publication": { "status": "research-draft", "adjudicationStatus": "unreviewed", "publishableCanonical": false, "generatedAt": "2026-09-13T13:26:56Z", "providers": [ "Claude" ], "breadth": "written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify", "pass": 2, "wave": 4, "engine": "claude" }, "metaModel": { "id": "THING-Q2945123", "registryId": "vr.tr.center-of-mass", "name": "center of mass", "version": "0.2.0-wave.4", "entryKind": "thing", "family": "Thing Registry", "domain": [ "XCT.QLT" ], "status": "research-draft" }, "canonicalUrl": "https://ver.cy/models/thing/q2945123/", "model": { "registry_id": "vr.tr.center-of-mass", "name": "center of mass", "purpose": "Let an agent explain the centre of mass and its relatives, relay definitions, calculation and applications from mechanics references, describe centroids, barycentres and centres of buoyancy, and distinguish centre of mass from centre of gravity in non-uniform fields, from the centroid of a shape and from the centre of pressure.", "definition": "The unique point of a body or system where its mass is concentrated for the purposes of mechanics, so that the body balances there and external forces act on it as if applied at that point, coinciding with the centre of gravity in a uniform gravitational field and with the geometric centroid for uniform density, with the triangle centroid a classic example, the barycentre of orbiting bodies an astronomical case, and the centre of buoyancy the analogous point for displaced fluid.", "what_it_is_for": "Analysing balance, motion and stability.", "affordances": [ "explain the concept", "relay calculation and applications", "describe related points", "distinguish related concepts" ], "distinguishing_features": [ "Mass-weighted point", "Newtonian mechanics", "Several related points", "Stability analysis" ], "appearance": "Not a visible object; a point in a body or system.", "visual_identification": [ "Mass-weighted average position", "Centre of gravity, centroid, triangle centroid, barycentre, centre of buoyancy", "Centre of gravity differs in non-uniform fields; the centroid is geometric; centre of pressure concerns fluid forces" ], "physical_properties": [ { "quantity": "definition", "typical_range": "mass-weighted mean of positions", "unit": "note", "note": "" }, { "quantity": "Earth-Moon barycentre", "typical_range": "about 4670 km from Earth s centre", "unit": "note", "note": "inside the Earth" }, { "quantity": "triangle centroid", "typical_range": "intersection of medians", "unit": "note", "note": "" } ], "families_and_kinds": [ "centre of mass of rigid bodies and systems", "centre of gravity in uniform and non-uniform fields", "centroids of shapes including the triangle centroid", "barycentres of orbiting systems", "centre of buoyancy in fluids" ], "related_models": [ { "relation": "is a kind of", "target": "point in physical space", "why": "in registry terms" }, { "relation": "is a kind of", "target": "position vector", "why": "in registry terms" }, { "relation": "coincides with", "target": "centroid", "why": "for uniform density" }, { "relation": "is contrasted with", "target": "center of pressure", "why": "for fluid forces" } ], "identifiers": [], "standards_and_regulation": [ "No regulation; engineering standards for stability and loading" ], "failure_modes_and_hazards": [ "Confusing centre of mass and centre of gravity", "Instability from misplaced loads", "Registry aliases mixing related but distinct points" ], "in_scope": [], "out_of_scope": [], "characteristics": [] }, "sources": [], "structure": { "bundles": [ { "id": "understand", "name": "Understand", "description": "What the centre of mass is.", "rationale": "Science.", "layers": [ { "id": "definition", "name": "Definition", "description": "Definition.", "findings": [ { "id": "definition-finding", "name": "Definition", "description": "Definition.", "questions": [ { "text": "What is the centre of mass, and how does it differ from centre of gravity, centroid and centre of pressure?", "kind": "definition" }, { "text": "Is the question about mechanics, geometry, astronomy or fluids?", "kind": "boundary" } ] } ] }, { "id": "related", "name": "Related", "description": "Related points.", "findings": [ { "id": "related-finding", "name": "Related", "description": "Related.", "questions": [ { "text": "What are the triangle centroid, the barycentre and the centre of buoyancy?", "kind": "definition" }, { "text": "Which entry fits the specific point?", "kind": "action" } ] } ] } ] }, { "id": "compute", "name": "Compute", "description": "Calculation.", "rationale": "Practice.", "layers": [ { "id": "methods", "name": "Methods", "description": "Methods.", "findings": [ { "id": "methods-finding", "name": "Methods", "description": "Methods.", "questions": [ { "text": "How is the centre of mass calculated for particles, shapes and composite bodies?", "kind": "action" }, { "text": "Which references are standard?", "kind": "provenance" } ] } ] }, { "id": "experiment", "name": "Experiment", "description": "Finding it experimentally.", "findings": [ { "id": "experiment-finding", "name": "Experiment", "description": "Experiment.", "questions": [ { "text": "How is the centre of mass found by suspension and balancing?", "kind": "measurement" }, { "text": "Which sources are cited?", "kind": "provenance" } ] } ] } ] }, { "id": "apply", "name": "Apply", "description": "Applications.", "rationale": "Application.", "layers": [ { "id": "engineering", "name": "Engineering", "description": "Engineering.", "findings": [ { "id": "engineering-finding", "name": "Engineering", "description": "Engineering.", "questions": [ { "text": "How is centre of mass used in vehicle, aircraft and ship stability and in structures?", "kind": "provenance" }, { "text": "Which entry fits ship stability?", "kind": "action" } ] } ] }, { "id": "astronomy", "name": "Astronomy", "description": "Astronomy and sport.", "findings": [ { "id": "astronomy-finding", "name": "Astronomy", "description": "Astronomy.", "questions": [ { "text": "How do barycentres govern orbits, and how do athletes use centre of mass in movement?", "kind": "provenance" }, { "text": "Which entry fits barycenter?", "kind": "action" } ] } ] } ] }, { "id": "context", "name": "Context", "description": "Theory and history.", "rationale": "Context.", "layers": [ { "id": "theory", "name": "Theory", "description": "Theory.", "findings": [ { "id": "theory-finding", "name": "Theory", "description": "Theory.", "questions": [ { "text": "Why does the centre of mass move as if all external forces act on it, and what changes in relativity?", "kind": "provenance" }, { "text": "Which entry fits Newton s laws of motion?", "kind": "action" } ] } ] }, { "id": "history", "name": "History", "description": "History.", "findings": [ { "id": "history-finding", "name": "History", "description": "History.", "questions": [ { "text": "How did Archimedes and later scientists develop the concept?", "kind": "provenance" }, { "text": "Which entry fits the history of mechanics?", "kind": "action" } ] } ] } ] } ] }, "openQuestions": [ "Should centroid, barycentre and centre of buoyancy be separate primary entries?", "How should mechanics references be linked?", "The registry entry has merged aliases naming distinct points; should they be split off?" ], "statistics": { "bundles": 4, "layers": 8, "findings": 8, "questions": 16 } }, "draft": { "generator": "vr.draft.v3", "status": "draft-generated", "researched": false, "archetype": "abstract concept", "method": "Written from the archetype playbook - what this kind of thing needs beyond identity and provenance - and from the structure that recurred across 6,333 models already researched by two engines. Applied to this entry by rule. No source was read for this thing and no claim here is researched. This entry carries no facets of its own, so they were inferred from its domain - a guess about a whole domain applied to one thing.", "facetsInferred": true, "nextPass": "A researcher replaces this draft with a sourced specification. Treat every sentence below as a proposal to argue with.", "purpose": "Give an agent a durable, checkable way to recognise a center of mass, record what state it is in, and decide what may be done with it.", "whatItIs": "Let an agent explain the centre of mass and its relatives, relay definitions, calculation and applications from mechanics references, describe centroids, barycentres and centres of buoyancy, and distinguish centre of mass from centre of gravity in non-uniform fields, from the centroid of a shape and from the centre of pressure.", "characteristics": { "substance": "abstract", "origin": "conceptual", "agency": "inert" }, "whatYouCanDoWithIt": [ "observed and measured" ], "distinguishingFeatures": [ "Names folded into this entry, which a task may need to split apart again: center of gravity, centroid, barycenter, centers of gravity in non-uniform fields, triangle centroid, centre of buoyancy, center of gravity of the surface, Spieker center.", "8 finer distinctions are held as aliases rather than separate entries, because telling them apart needs a task that asks for it.", "Described in 63 Wikipedia languages, which is a measure of how widely the thing is known, not of how important it is." ], "openQuestionsForResearch": [ "Which of the bundles below does a real task actually need, and which are ceremony?", "What does this thing have that the facets do not capture at all?", "Which neighbouring kind is most often confused with a center of mass, and on what evidence are they told apart?" ], "whatItIsMadeOf": "an abstraction with no physical instance", "physicalCharacter": [ "Does nothing on its own; everything it does, something else did to it.", "These come from the domain this entry sits in rather than from the entry itself, so treat them as a first guess about the whole domain applied to one thing." ], "whatCanBeDoneWithIt": [ "observe it, measure it, record its state" ], "howItIsRecognised": [ "Nothing to see. What is recognised is an instance of it, and which instances count is exactly what is argued about." ], "relatedModels": [ { "relation": "covers", "note": "Finer kinds folded into this entry because telling them apart needs a task that asks for it. Each is a model waiting to be split out when one does.", "targets": [ "center of gravity", "centroid", "barycenter", "centers of gravity in non-uniform fields", "triangle centroid", "centre of buoyancy", "center of gravity of the surface", "Spieker center" ] } ], "standing": "Described in 63 Wikipedia languages, which measures how widely it is written about rather than how important or how common it is. 8 finer distinctions are held inside this entry as names rather than as separate models.", "structure": { "bundles": [ { "id": "identity-and-classification", "name": "Identity, naming and classification", "description": "How an agent tells one center of mass from another, and a center of mass from things that resemble it.", "rationale": "Recognition comes before every other claim. Without stable identity nothing else in the model can be trusted to be about the same thing twice.", "layers": [ { "id": "naming-and-identifiers", "name": "Names and identifiers", "description": "The names this thing goes by and the identifiers that survive translation and time.", "findings": [ { "id": "preferred-name-and-aliases", "name": "Preferred name, aliases and local names", "description": "Which name to use, which names mean the same thing, and which merely sound similar.", "questions": [ { "id": "preferred-name-and-aliases-q01", "text": "What identifies and describes the name of a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "preferred-name-and-aliases-q02", "text": "Who or what asserted this about the name of a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "preferred-name-and-aliases-q03", "text": "What may an agent decide or do once the name of a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] }, { "id": "stable-identifiers", "name": "Stable identifiers and external keys", "description": "Identifiers that keep pointing at this kind of thing across systems and languages.", "questions": [ { "id": "stable-identifiers-q01", "text": "What identifies and describes an identifier for a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "stable-identifiers-q02", "text": "Who or what asserted this about an identifier for a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "stable-identifiers-q03", "text": "What may an agent decide or do once an identifier for a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] } ] }, { "id": "classification-and-granularity", "name": "Classification and granularity", "description": "Where a center of mass sits among kinds, and how finely a task needs to cut it.", "findings": [ { "id": "kind-and-parents", "name": "Kind, parents and neighbouring kinds", "description": "The classes this thing belongs to and the ones it is next to.", "questions": [ { "id": "kind-and-parents-q01", "text": "What identifies and describes the kind of a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "kind-and-parents-q02", "text": "Who or what asserted this about the kind of a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "kind-and-parents-q03", "text": "What may an agent decide or do once the kind of a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] }, { "id": "distinguishing-features", "name": "Distinguishing features", "description": "What separates a center of mass from the things most often confused with it.", "questions": [ { "id": "distinguishing-features-q01", "text": "What identifies and describes what distinguishes a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "distinguishing-features-q02", "text": "Who or what asserted this about what distinguishes a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "distinguishing-features-q03", "text": "What may an agent decide or do once what distinguishes a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] } ] } ] }, { "id": "state-and-lifecycle", "name": "State and lifecycle", "description": "The states a center of mass passes through and the events that move it between them.", "rationale": "Most decisions about a thing depend on what state it is in now, which is a claim with a time on it, not a property.", "layers": [ { "id": "lifecycle-stages", "name": "Lifecycle stages", "description": "From coming into existence to ceasing to be one of these.", "findings": [ { "id": "stages-and-transitions", "name": "Stages and transitions", "description": "The stages worth naming and what moves a center of mass between them.", "questions": [ { "id": "stages-and-transitions-q01", "text": "What identifies and describes the lifecycle of a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "stages-and-transitions-q02", "text": "Who or what asserted this about the lifecycle of a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "stages-and-transitions-q03", "text": "What may an agent decide or do once the lifecycle of a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] } ] }, { "id": "observations-and-status", "name": "Observations and current status", "description": "What is observed about a center of mass, how often and by whom.", "findings": [ { "id": "observation-record", "name": "Observation record", "description": "How an observation of a center of mass is recorded so that it can be superseded rather than overwritten.", "questions": [ { "id": "observation-record-q01", "text": "What identifies and describes an observation of a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "observation-record-q02", "text": "Who or what asserted this about an observation of a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "observation-record-q03", "text": "What may an agent decide or do once an observation of a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] } ] } ] }, { "id": "definitions-in-contest", "name": "Definitions and who holds them", "description": "What center of mass is taken to mean, and by whom.", "rationale": "When a field disagrees about a concept, the disagreement is the content. A model that picks one definition silently destroys the information.", "layers": [ { "id": "competing-definitions", "name": "Competing definitions", "description": "The main readings and the traditions behind them.", "findings": [ { "id": "definition-map", "name": "Definitions and their holders", "description": "Each definition with the school or body that holds it.", "questions": [ { "id": "definition-map-q01", "text": "Which definitions of center of mass are in use, and which tradition or body holds each?", "kind": "definition" }, { "id": "definition-map-q02", "text": "What turns on the difference between them in practice?", "kind": "boundary" } ] } ] }, { "id": "operationalisation", "name": "Operationalisation", "description": "How it is measured or applied when it has to be.", "findings": [ { "id": "operational-record", "name": "Measures and proxies", "description": "Instruments and indicators used to stand in for it.", "questions": [ { "id": "operational-record-q01", "text": "How is center of mass operationalised or measured in practice, and by what instrument?", "kind": "measurement" }, { "id": "operational-record-q02", "text": "What does that operationalisation leave out, and when does that matter?", "kind": "boundary" } ] } ] } ] }, { "id": "instances-and-use", "name": "Instances, use and consequence", "description": "What counts as an instance of center of mass and what follows from calling something that.", "rationale": "Applying a concept is an act with consequences, so a model must say what the label licenses and what it does not.", "layers": [ { "id": "instances", "name": "What counts as an instance", "description": "Clear cases, borderline cases and non-cases.", "findings": [ { "id": "instance-tests", "name": "Tests for an instance", "description": "What would settle whether something falls under it.", "questions": [ { "id": "instance-tests-q01", "text": "What would settle whether something is an instance of center of mass?", "kind": "boundary" }, { "id": "instance-tests-q02", "text": "Which borderline cases are argued about, and on what grounds?", "kind": "definition" } ] } ] }, { "id": "consequence", "name": "Consequence of application", "description": "Rights, duties or decisions that follow from the label.", "findings": [ { "id": "consequence-record", "name": "What the label licenses", "description": "What an agent may do once something is classified this way.", "questions": [ { "id": "consequence-record-q01", "text": "What follows practically once something is treated as center of mass?", "kind": "action" }, { "id": "consequence-record-q02", "text": "What must an agent not infer from the label alone?", "kind": "action" } ] } ] } ] }, { "id": "provenance-and-evidence", "name": "Provenance, evidence and time", "description": "Where every claim about a center of mass came from and when it held.", "rationale": "A claim without a source and a time cannot be superseded, only overwritten, and an agent that overwrites loses the ability to explain itself.", "layers": [ { "id": "source-and-authority", "name": "Source and authority", "description": "Who said it, on what evidence, and how strongly.", "findings": [ { "id": "claim-provenance", "name": "Claim provenance and confidence", "description": "The authority behind each claim about a center of mass and how confident it is.", "questions": [ { "id": "claim-provenance-q01", "text": "What identifies and describes a claim about a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "claim-provenance-q02", "text": "Who or what asserted this about a claim about a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "claim-provenance-q03", "text": "What may an agent decide or do once a claim about a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] } ] }, { "id": "time-and-versions", "name": "Time, versions and supersession", "description": "When a claim was true, when it was learnt, and what replaced it.", "findings": [ { "id": "validity-and-supersession", "name": "Validity period and supersession", "description": "How an old claim about a center of mass is retired without being erased.", "questions": [ { "id": "validity-and-supersession-q01", "text": "What identifies and describes the validity of a claim about a center of mass, and in what units or vocabulary?", "kind": "definition", "answer_data": [ "identifiers", "types and classes", "values with units", "explicit unknowns" ] }, { "id": "validity-and-supersession-q02", "text": "Who or what asserted this about the validity of a claim about a center of mass, by which method, and when was it true?", "kind": "provenance", "answer_data": [ "authority", "method", "evidence", "event time", "knowledge time" ] }, { "id": "validity-and-supersession-q03", "text": "What may an agent decide or do once the validity of a claim about a center of mass is known, and what must it refuse?", "kind": "action", "answer_data": [ "permitted actions", "preconditions", "refusals", "escalation" ] } ] } ] } ] } ] }, "statistics": { "bundles": 5, "layers": 10, "findings": 12, "questions": 32 } } } }