- Fill a sink or any container with fresh, clean water.
- Now, cut out some cardboard or heavy paper in the shape of a boat.
- Make your boat small, about the size of a postage stamp.
- Once your boat is cut out, make a small notch in the back.
- Put a small dab of soap in the notch.
- Set your boat in the water and watch it speed around!
Scientific Principle at Work
Surface tension represents the way liquids, like water and vegetable oil, act when they are mixed together. Surface tension is measured by scientists in a unit called “dynes” per centimeter. Tension is created by the attraction of molecules toward the interior.
Soap has molecules that are designed by chemists to dissolve in water. The action of dissolving reduces surface tension mixing soap molecules among the water molecules on the surface of the water. As the soap dissolves in the water, it creates a force that moves the boat forward.
Note: If you’re under the age of 18, be sure your parent or guardian knows what you are doing. Some of these experiments require the use of simple household tools, such as scissors and knives, and some could make a mess. Ask your parent or another adult to help.