Water, splashes & buoyancy
Before you start
Why does wood float while metal tends to sink? How does a falling object transfer energy into waves and splashes? Try it in an interactive tank.
The setupA transparent tank holds water of density 1000 kg/m³. Lift, submerge or release a sphere of radius 0.43 m. A gold probe measures gauge pressure below the surface.
What to do and noticeGrab the sphere, push it under water, release it and watch where it settles. · Increase the release height to compare splashes and returning droplets; try slow motion. · Change density and probe depth; connect the visible changes with Fᵦ = ρgV and p − p₀ = ρgh.
Predict firstWhat changes when an equally sized sphere becomes denser?
Explain pressure, buoyancy and impact energy through experiments you can manipulate.
Prerequisites: Mass measures inertia; density is mass per unit volume.Start with equal volume
Predict firstWhat changes when an equally sized sphere becomes denser?
Weight mg increases with mass, but buoyancy at a given submerged volume does not. If the sphere is less dense than water, partial immersion is enough to balance its weight.
How to observe
- Grab the sphere, push it under water, release it and watch where it settles.
- Increase the release height to compare splashes and returning droplets; try slow motion.
- Change density and probe depth; connect the visible changes with Fᵦ = ρgV and p − p₀ = ρgh.
Model notes
Water is simulated as equal-mass particles in three dimensions with iterative density constraints. Sphere collisions displace the liquid; detached parcels fall under gravity and can rejoin it. A continuous surface is reconstructed from particle depth and density gradients, with refraction, Fresnel reflection and absorption. Finite particle resolution cannot fully resolve fine spray or entrained air. Sphere buoyancy still uses submerged volume, with approximate drag and added mass; this is not an engineering load calculation.