Water pushes up.
Buoyant force (upthrust) acts upwards. Weight acts downwards. An object floating at rest has equal upward and downward forces.
THE WATER LAB
● Virtual experimentBig ideas. A little water.
Predict, drop, observe. Discover what keeps things afloat.
LIVE 3D TANK
Ready to testWooden block
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↑ Buoyant force↓ Weight↑ Floor support
Drag to rotate · Scroll to zoom
DISPLACED WATER— mL
↑ BUOYANT FORCE— N
↓ WEIGHT1.96 N
✦
Two forces. One discovery.
Water pushes up. Gravity pulls down. Place the object in water to compare the forces.
YOUR SCIENCE NOTEBOOK
Observe. Record. Explain.
| Trial / object | Water | Mass (g) | Volume / capacity (mL) | Displaced (mL) | Upthrust (N) | Weight (N) | Prediction | Result |
|---|---|---|---|---|---|---|---|---|
| Your discoveries will appear here. Run an experiment, then record your result. | ||||||||
Results stay in this tab during your session. Export them before closing the page.
Make room for water.
An object displaces water when it takes up space in it. The buoyant force equals the weight of the displaced water.
Same clay. New possibility.
A hollow bowl can displace more water before water enters it. Reshaping changes its capacity to displace water, but keeps the clay’s mass and weight the same.
Teacher notes & model guide
Based on the supplied P6 Water pages 16–20. Suggested sequence: compare wood and metal; compare the 200 g clay ball and 200 g clay bowl in fresh water; then change one variable in Your experiment. Ask students to explain the floating bowl using displaced water and balanced forces.
Calculations use g = 9.8 N/kg. In fresh water, 1 mL has a mass of 1 g. Upthrust = displaced volume (mL) × water density (g/mL) × 9.8 ÷ 1000. Mass and volume presets are illustrative samples, not measurements of all real objects. The concentrated salt-water option is a model liquid, not ordinary seawater.
Tank water level is held constant, as in an overflow can; readings show the water displaced by the immersed object. Motion is a smooth illustrative transition to calculated equilibrium, not a fluid dynamics simulation. Air buoyancy, surface tension and splashing are omitted. Arrows share one scale with an upper display limit; use numerical readings for exact comparisons. A sinking object at the bottom also has an upward support force from the tank floor.
The bowl can exclude 600 mL before its rim floods. Its clay occupies 100 mL. Once overloaded, the open bowl fills with water; the model counts only clay and solid cargo as displaced volume. Exactly matching capacity is treated as flooding. The custom block can suspend fully underwater when its average density exactly matches the water.