Can water walk upwards against gravity? No, not really, but what makes water seem like it defies gravity is what we’re going to explore in this easy science experiment.
Using us a few common kitchen items, kids can see the process of capillary action and learn about how attraction and adhesive forces cause the water to move from one glass to another. Detailed instructions, a simple scientific explanation, and a demonstration video are included below.
- 2 glasses of equal height
- Food Coloring (optional)
- Paper Towel
Step 1 – Get your supplies ready. Then position the two empty glasses so they are about 3 inches apart. Pour water into one of the glasses until it is about halfway full.
Step 2 – Next add a few drops of food coloring to the water. You can choose any color. Stir the water until the food coloring is fully combined.
Step 3 – Take a strip of paper towel that is about 1-2 inches wide and 12 inches long. We used one section of paper towel and folded it in half until it was the correct width.
Step 4 – Place one end of the paper towel into the glass with the water. Then place the other end into the glass that is empty.
Take a moment to make some observations. What happened to the paper towel that was placed in the water? Do you think it is possible for the water in the first glass to move to the empty glass? Write down your hypothesis (prediction) and then leave the glasses to sit and come back to check on them in about an hour.
Step 5 – Return to the glasses and make some observations. What happened during the hour you were waiting? What do you think will happen if you wait a little longer. Do you think all the water in the first glass will move to the second glass? Why or why not? Write down your hypothesis (prediction) and then leave the glasses to sit and come back to check on them in two hours.
The water appears to defy gravity, but in reality, it moves because of a process called capillary action. Water is able to move against the force of gravity because water molecules stick to each other AND they stick to the fibers of the paper towel. As water molecules are attracted to the fibers of the paper towel, they pull other water molecules with them.
The adhesive forces between the water and the fibers of the paper towel are stronger than the cohesive forces between the water molecules. As a result, the water travels up and across the paper towel out of one glass and into another.
Capillary action is the combined force of attraction among water molecules and with the molecules of surrounding materials.
More Science Fun
Eventually, the water will stop moving over once both cups are filled with the same amount of water. Expand on the experiment, by estimating how long it will take for the water to move to the second jar. Then set a timer and find out how close your estimate was.
In addition, you can also try these other fun experiments using water and food coloring:
- Color Changing Walking Water Science Experiment – Much like the regular walking water science experiment, but with an added “colorful” twist.
- Coloring Changing Water Science Experiment – Science or magic? Try this experiment at home with your kids and watch their eyes light up as you pour the liquid into the bowl and “create” a new color.
- Water Temperature Science Experiment – See thermal energy in action and explore the concept hands-on as you observe how water molecules move faster when hot and slower when cold.
I hope you enjoyed the experiment. Here are some printable instructions: