I’ve created a separate category for blogs about Aya’s experiments (see “Experiments” – what a no-brainer, eh?). Last week we performed a so-called “bottle tornado,” where we created a water vortex using two PET bottles.

For this experiment, we used the following: 2 PET bottles, one make-shift washer (just one of the caps for the PET bottle, with a hole bored through it), tape, and some food coloring.

Aya fills one of the PET bottles with water, about 2/3 full.

Aya then adds food coloring to the water. This is only optional, actually. Aya chose yellow, her favorite color!

The mouth of the second bottle is then balanced on top of the make-shift washer. The two bottles are fastened with tape.

The bottles are then turned over. With Tatay’s help, Aya then moves the top bottle in rapid circles.

After giving the bottle a good spin, a water vortex is formed – success! 🙂

Here’s a closeup of the water vortex formed at the top bottle. Can you see it?

The principle is simple – water is held in the top bottle by the air pressure in the lower bottle, and the surface tension of the water in the “washer.” Spinning the bottle creates a turning force in the water that breaks the surface tension, allowing the water to flow. The air in the lower bottle is then forced into the top.

Till next experiment! 🙂 🙂 🙂