They never stop moving
Drop a grain of purple crystal into water. Pink streaks spread out. After a long while the whole glass is pink. Nobody stirred it.
Step 1 of 4
- A burning incense stick sits in one corner.
- Its particles wander off and bounce about.
- More and more particles spread out.
- After a while the smell reaches the door.
New word
- Diffusion — particles mixing by moving around on their own.
The rule
Particles never stop moving. They bump into each other and spread out. They spread faster when the water or air is warm.
This is because warm particles move faster.
In hot water the crystal spreads fastest. In ice-cold water it spreads slowest.
Three glasses, one clock. Slide the time.
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