A LITTLE CONTEXT. A BETTER EXPERIMENT.
Discovery guide v1.0.0 · Changelog
Float or Sink Lab — Density & Buoyancy Simulator
Let the liquid have a vote.
Float or Sink Lab is an interactive density and buoyancy simulator. Compare a solid object with a hollow hull, change the surrounding liquid and explore how displacement supports a load. The diagrams, measurements and cargo challenge connect floating and sinking to quantities you can change.
Open Float or Sink Lab ↗Free to start in your browser. The interactive tool uses JavaScript.
Try a small experiment.
- Start with the block experiment. Change the material or liquid and predict whether the object will float.
- Try a hollow steel hull. Compare its mass with the amount of liquid its shape can displace.
- Add cargo gradually and watch the available buoyancy and submerged volume. Compare using either measurement system.
A couple of useful questions.
How can a steel boat float when a solid steel block sinks?
A hollow hull can displace a large volume of water relative to its total mass. The relevant comparison includes the whole object and its enclosed space, not just the density of the steel.
What is buoyant force?
Buoyant force is the upward force associated with displaced fluid. In the basic model it equals the weight of the displaced liquid. A floating object settles where that force balances its weight.
Know what the tool represents.
The illustrations simplify shapes and equilibrium. They help explain displacement and loading, rather than certify a real vessel’s stability or capacity. Model assumptions and equations are available inside the tool.
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Guide v1.0.0 · Updated November 1, 2026. Controls can evolve; the tool’s own changelog and model notes describe its current behavior.