Vernier Software and Technology
Vernier Software & Technology

Cartesian Diver


A Cartesian diver is a classic science experiment, named for René Descartes, which demonstrates the principle of buoyancy. The “diver” is a small, rigid tube (such as an eye dropper), open at the bottom end and sealed at the top. When immersed in an airtight, but flexible container of water, the diver will float near the water surface. When the container is squeezed (light pressure applied by hand), the diver will sink to the bottom of the container. Increasing the container’s pressure by squeezing affects the least dense material in the container, which is the air inside the diver. This occurs because of Pascal's Principle, which states that pressure on a fluid is transmitted unchanged throughout the fluid. In this project, your challenge is to build a sensor-controlled robotic device to replicate a Cartesian diver.

Design Requirements

In this project, you will design and build a stationary air-pumping station for a Cartesian diver apparatus. Your device should replicate the pressurization caused by squeezing a handheld bottle. You will use a LEGO Pneumatic Hand Pump and Vernier Gas Pressure Sensor to automatically pressurize the bottle causing the diver to sink to the bottom. (Note: You will not be building a robotic device to actually squeeze the bottle.) Once your diver has reached the bottom of the bottle, you should use a LEGO Pneumatic Switch to ease the pressure on the bottle allowing the diver to rise to the surface. Your pressurization and release cycle should be determined by feedback from the Gas Pressure Sensor.

You are strongly encouraged to use the Engineering Design Method and your creative imagination when tackling this challenge. The Engineering Design Method will help you develop a successful working robot. A little planning will save you time and frustration, especially when working on more complicated projects.

Sensors and Equipment

This project features the following Vernier sensors and equipment.

Additional Requirements

You will also need NXT Sensor Adapter and a LEGO MINDSTORMS NXT robotics system.

Standards Correlations

See all standards correlations for Vernier Engineering Projects with LEGO® MINDSTORMS® Education NXT »

Project 7 from Vernier Engineering Projects with LEGO® MINDSTORMS® Education NXT Lab Book

<i>Vernier Engineering Projects with LEGO<sup>®</sup> MINDSTORMS<sup>®</sup> Education NXT</i> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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