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Pepper on the run
Materials
a shallow bowl, water, ground black pepper, a few drops of dish soap on a plate
Steps
- Pour about an inch of water into the bowl.
- Sprinkle a little pepper over the water. Can you see that it floats?
- Dip a finger into the water. Does anything happen?
- Now dip the same finger into the dish soap, then gently touch the middle of the water. Watch the pepper!
What happens?
The surface of water holds together like a thin skin. This is called surface tension, and it's why the pepper floats. Soap makes the surface tension weaker where your finger is. The water around it pulls outward and carries the pepper to the edge. Source: Fleet Science Center.
Safety for grown-ups
Use only a few drops of dish soap. Wash hands afterward, and don't rub your eyes with pepper or soap on your fingers. If soap gets in your eyes, rinse with water. Don't taste. An adult should supervise.