Float or sink?
Drop a leaf and a coin into water. The leaf floats on top, but the coin sinks to the bottom. Why? The answer is density.
Density means how heavy an object is for its size — how tightly its stuff is packed together.
Key idea
If an object is less dense than water, it floats. If it is more dense than water, it sinks.
Everyday examples
Some things are light for their size and float:
- Wood, cork and dry leaves float.
- An empty capped bottle floats because it is full of air.
- Ice floats on your cold drink.
Some things are heavy for their size and sink, like a stone, a coin or an iron nail.
Remember
- Less dense than water → floats.
- More dense than water → sinks.