1. CAN YOU CREATE A SUBMARINE USING A PEN CAP?

A. Materials needed:

1. A bottle filled with water.
2. A ball pen top.
3. A gum (or paper clip)

B. Instructions:

1. Attach some gum or paper clips to the extended part of the pen cap as shown on the top right-hand corner of this poster. The driver is made.

2. Test the driver in water to ensure that it sinks upright.

3.  Place the driver in a bottle filled with water and close the bottle. The pen cap should float upright.

4. Gently squeeze and release the bottle. The driver should sink when you squeeze it and float wh

HOW DOES THE CARTESIAN DRIVER WORK?

The driver floats when the bottle is squeezed because the water rushes to fill the hollow spaces of the pen cap, making it more dense. This makes the weight of the pen cap greater than the buoyant force (upward force exerted on the pen cap by the water), so the pen cap sinks.

When the bottle is released, the water rushes out, so the buoyant force overcomes the weight of the pen cap, so it floats.

TAKING IT FURTHER

Try this experiment with different liquids such as salt solution.

Note: parental guidance is needed when experimenting with liquids other than water!

Share your results with us @eduspots