Physics · Grades 8–11
Displacement, density and buoyancy · Revision sheet
Use displaced fluid weight and avoid shape-only explanations of floating.
Learn the idea
Buoyant force
The upward buoyant force equals the weight of displaced fluid in the static model.
Displaced volume
A fully submerged object's displaced volume equals its external submerged volume, not an arbitrary container reading.
Floating balance
An object floating at rest has buoyancy balancing its weight.
Density matters
Average density includes enclosed spaces. A hollow vessel can float even when its solid material is denser than water.
Explain without looking
- Does an upward buoyant force guarantee that an object rises?
- A floating object weighs 20 N in a liquid with g = 10 N/kg. Find the mass of displaced liquid.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.