The Cartesian Diver: Application Experiment

Aim

This is an application of the rule just discovered regarding buoyancy. It draws in knowledge from gases as well.

Prior Knowledge

• Establishment of Archimedes Prinicple: What does the buoyant force depend on?
• Compressibility of gases.
• Transmission of pressure through a fluid.
• Relationship between pressure and volume.

Description of the Experiment

An open vial is filled with water and just enough air so that it will float. It is placed in a plastic bottle containing water and the cap is replaced. The container is then given a hard squeeze. Predict what will happen to the vial as pressure is applied to the container.

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Questions

If you are struggling to explain what you saw, or want to test the validity of your explanation, try answering the following questions:

• What happens to the air in the vial when the bottle is squeezed?



• What happens to the mass of the vial?



• Use the rule you just discovered to explain what you saw.