Archimedes' buoyancy principle
The hydrostatic upward force equals displaced-fluid weight.
Key knowledge
For a body partially or fully immersed in a static fluid, the hydrostatic buoyant force equals the weight of fluid displaced. With uniform fluid density and gravity, its magnitude is F_B = ρ_fluid g V_displaced.
Values and equations
F_B = ρ_fluid g V_displaced
- F_B
- Upward hydrostatic buoyant-force magnitude N
- ρ_fluid
- Uniform displaced-fluid mass density kg m⁻³
- g
- Uniform gravitational-acceleration magnitude m s⁻²
- V_displaced
- Volume of fluid displaced by the submerged body portion m³
Conditions and scope
- Fluid pressure reaches the surrounding wetted surface; sealed contact with the bottom is outside this model.
- Use the submerged displacement volume, not automatically the body's whole volume.
- Surface-tension forces and dynamic lift are excluded; buoyancy equals body weight only when the full vertical force balance allows it.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
OpenStax 14.4: pressure-force argument, displaced-fluid weight and partial immersion.
2026-10-10 · Static-fluid pressure contribution only; no general claim that every immersed body floats or has this force under arbitrary contact conditions.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Scope or convention differs
Hydrostatic buoyancy in homogeneous fluid equals the weight of displaced fluid, including partial immersion.
The wetted-surface argument supports the formula; sealed-bottom contact and surface tension require separate forces.
Indian Institute of Technology Kanpur · NPTEL
- Fluid Mechanics · Buoyancy IndiaEnglish
Chapter2 Lecture5: entire-surface hydrostatic argument; Archimedes principle; partial immersion
- Fluid Mechanics · Buoyancy
Entry details
Permanent link to this entry ↗- Record identity
- physics-buoyancy
- Revision
- core.1
- Structured reference record
- Essential core · first collection · University core expansion