Cartesian Diver
Recommended for grades 6–12.
Introduction
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.
Objectives
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. 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.
Sensors and Equipment
This project/activity requires each of the following Vernier sensors and equipment (unless otherwise noted):
Additional Requirements
You will also need NXT Sensor Adapter and a LEGO MINDSTORMS NXT robotics system.
Download Experiment Preview
The student-version preview includes:
- Step-by-step instructions for computer-based data collection
- List of materials and equipment
The preview does not include essential teacher information, safety tips, or sample data. We strongly recommend that you purchase the book for classroom use.
Standards Correlations
See all standards correlations for STEM 2 with Vernier and LEGO MINDSTORMS NXT »
Included in the Lab Book
Vernier lab books include a CD with word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.