Propelling a Toy Boat with Detergent
You will need: Card, scissors, pencil, large plate or bowl, water,
In this experiment we will try to lessen the surface tension of water at a certain area, and see what effect it has.
First, draw a simple boat shape on a piece of card, to the dimensions indicated in the diagram. Cut this out carefully, including the triangle.
Fill a large plate with water and launch your boat to make sure it floats well.
Now take a little detergent powder on the blade of a screwdriver or the end of a knife, and drop it carefully into the small, triangular opening that you have cut in the stern of your small boat.
Within a few seconds the boat will be traveling forward through the water, as the detergent breaks down the surface tension and tries to expand through the narrow opening in the rear of the model.
Try repeating this experiment, with a drop of oil from oil can, in place of the detergent, or by floating a small piece of camphor at the rear of the model boat. Both oil and camphor have an effect on surface tension, as you will notice.