- Try spinning a smooth rubber ball in a bowl of water. What happens?
- Try the same with the tennis ball. What happens to it? Why?
- Place two things on a cutting board in wood, for example a button and a eraser. Tilt the board a little.
What happened? Which object travels fastest? Why?
Try other things too.
- Repeat the same experiment with a metal or glass tray.
What happens? Why?