Have you ever seen water walk? It’s not magic, it’s science! This fun and easy experiment will show you how water can move up a paper towel, even against gravity.
What to get:
- Two clear cups
- Food coloring (optional)
- Paper towel
What to do:
- Fill one cup with water.
- Add a few drops of food coloring to the water, if desired.
- Cut a piece of paper towel that is long enough to reach from the bottom of one cup to the top of the other cup.
- Place one end of the paper towel in the cup with the water.
- Place the other end of the paper towel in the empty cup.
- Wait a few minutes.
The science behind the experiment:
You will see the water slowly “walk” up the paper towel, from the cup with the water to the empty cup. This is because of a process called capillary action. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.
In this experiment, the water molecules are attracted to the fibers of the paper towel. This attraction is called adhesion. The water molecules are also attracted to each other, which is called cohesion. The combination of adhesion and cohesion is what causes the water to move up the paper towel.
This same process is what allows plants to get water from their roots to their leaves. The water in the soil is able to move up through the plant’s roots and stems because of capillary action.
The walking water experiment is a fun and easy way to learn about capillary action. It’s also a great way to get kids interested in science!
- You can try using different colors of food coloring to create a rainbow effect.
- Try using more than two cups to see how far you can make the water walk.
- Experiment using different types of paper towels to see if it affects the speed.