Why do some things sink?
Things sink when they're heavier than the water they push out of the way.
Pip’s answer
- Things sink when they're heavier than the water they push out of the way.
- A rock packs lots of stuff into a small space, so it drops down. Plop!
- A ball full of air is light for its size, so water holds it up.
- Ooh, giant steel ships float because they hold so much air inside!
For grown-ups
Whether something floats or sinks depends on density, how much mass is packed into its volume, compared with water. Objects denser than water sink, and less dense objects float. Shape matters too: a lump of clay sinks, but the same clay shaped like a boat can float.
Ask your child: Which toys in the bath do you think will float or sink?
More questions kids ask
- ⛵Why do boats float?
- 🦆Why do ducks float?
- 🎈Why do balloons float away?
- 🍎Why do things fall down?
- 🧲Why do magnets stick?
- 🫧Why are bubbles round?
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