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Experiment: Balloon in a bottle

Experiment: Flaschenballon Experiment: Ballon en Bouteille Eksperyment: Balon w butelce

Bottle Balloon - Drawing The balloon dives into the bottle.

The experiment is also kwown under the name Cartesian diver

The balloon in the bottle is a simple experiment to demonstrate the effect of static buoyancy. Although this is hydrostatic buoyancy, whereas a balloon in the air experiences aerostatic buoyancy, the effect is the same.

Warning: Only carry out this experiment if you know what you are doing. This experiment uses parts that can be swallowed. Therefore, take special care when children take part in the experiment.

Parts list

Material for the bottle balloon.

For the balloon:

  • A clear plastic tube (hardware store, pet store, aquarium supply).
  • A thread.
  • Several paper clips

And a flexible plastic bottle, with a wide enough neck for the balloon to fit through.

Building the balloon

Tube with thread.

First, cut the tube to the desired length. Then the thread is pulled through the tube.

Tube knotted in balloon shape.

Then the tube is pulled together with the thread to form a balloon shape, and then the thread is knotted.

The completed bottle balloon.

Then the paper clips are attached to the thread at the bottom. The paper clips have two functions. Firstly, they ensure that the tube openings stay down. Secondly, they are used to balance the balloon. The balloon should only have enough rising force to float in the water. It is easier to balance the balloon in an open container.


When the balloon is in the closed bottle, the pressure increases when the bottle is squeezed. The increase in pressure compresses the air bubble in the tube and the volume generating the buoyancy decreases - the balloon sinks. If, on the other hand, you reduce the pressure on the bottle, the pressure in the bottle decreases and the air bubble in the tube can expand - the buoyancy increases and the balloon rises.



This text was not written by a native speaker. If you notice any errors, have suggestions for improvement, or would like to make any other comments, please contact Volker Löschhorn.

bravo/balloon_in_a_bottle.txt · Last modified: 2021/05/02 15:37 by Volker Löschhorn