Oceanographers, marine geologists, and archeologists use sound to investigate objects below the surfaces of bodies of water. A signal is sent out and bounces back from a submerged surface. Scientists use the speed of sound in water and the time it takes for the signal to bounce back to calculate the depth of the object. Sonar is the name given to this system. The Motion Detector works in a similar manner. In this activity, you will use a Motion Detector to map objects on a simulated ocean floor.


  • Use a Motion Detector to measure distances.
  • Map simulated ocean floors.
  • Analyze graphs to find the heights of objects on a simulated ocean floor.