Join our 4-H teen as he steps into the world of hydro science.
What are we learning about today?
Imagine you have two glasses: one full of water and one empty. Would you be able to pour half of the water into the empty glass without picking either one up? It sounds impossible but with capillary action (when liquid flows in a narrow space), it can happen.
Paper towels are made of tiny fibers with small gaps between them. Water climbs through those gaps because of surface tension and, because water molecules stick to each other, and to the paper. This same process helps trees pull water in through their roots all the way up to their leaves!
You can make water walk all on your own.
What do you need?
- At least 3 clear glasses or cups – it works best with an odd number.
- Water
- Food coloring
- Spoon
- Half-sheet paper towels – one for each gap between your glasses.
Try it yourself.
- Start by lining up your glasses in a row.
- Fill every other glass with water so you've got one full, one empty, one full, one empty, and so on.
- Add a few drops of food coloring to each glass that has water. Don't use the same color twice in a row; it looks cooler when they mix.
- Give them each a stir – make sure to use a paper towel to wipe your spoon between colors so you don't mix the colors too early.
- Next, take your paper towels and fold each one into a narrow strip about one inch wide.
- Then fold it in half into a "V" shape. You want the V just tall enough to reach into both glasses when you connect them.
- Flip your "V" upside down and put one end into a glass with water and the other into an empty glass.
- Do that between every pair of glasses so each full one connects to an empty one with a paper towel bridge.
- Now observe
- At first you'll notice the ends of the paper towel getting wet
- After about 15-20 minutes, you'll start to see the colored water climbing up the paper towel and dripping into the empty glass.
- If you leave it for a few hours or overnight, the colors will mix right in the middle.
Open and print the supply sheet for yourself!
Want to learn more?