The Elliptic Orbit

David Pundak, Ort Braude College
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Initial Publication Date: April 27, 2010

Summary

This series of interactive lecture-demonstration questions probe student understanding of fundamental concepts concerning elliptic orbits. There are six basic conceptual questions on elliptic orbits. The questions deal with:

  • the kinematics of elliptic orbits
  • the potential and kinetic energy of the satellite along the orbit .

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Learning Goals

The goal is to develop a conceptual understanding of elliptic motion, satellite orbits, and the change between the kinetic and potential energy. The activity allows students to reveal the connection between satellite-velocity and acceleration along the elliptic orbit. Students could explore the gravitational force as a conservative force, and apply this understanding to a related -but not obviously identical- problem like comet-orbits.

Context for Use

Educational level: introductory physics or astronomy course.
Setting: Active-lecture question or workshop activity.
Time required: 15 minutes
Special equipment: computer with projector for instructor
Pre-requisite knowledge: basic mechanics: Newton's laws.

Description and Teaching Materials

The demonstration aspects of these questions will be done virtually with "Physlet," a physics java applet. [file 9435 '']

Teaching Notes and Tips

This is a nice activity to introduce Gravity and Kepler's Laws. It could also be used as an interactive demonstration or as an individual activity in the context of a studio class.


Assessment

Peer instruction: students discuss answers with other group members and try to arrive at a consensus. After peer instruction, a class discussion takes place where a representative from each groups presents their ideas. The instructor manages and presents main ideas regarding elliptic orbits. At the end, students analyze the orbit of Halley's Comet.

References and Resources

Physlets, Physics Applets, are small flexible Java applets designed for science education. You do not need to become a Java expert in order to use Physlets. The links on the right in the Physlet contain: tutorials, download instructions, and example problems to help you use Physlets in your teaching.

Physlet Physics: Interactive Illustrations, Explorations and Problems for Introductory Physics - Wolfgang Christian, Mario Belloni, Davidson College. Publisher: Addison-Wesley. Illustration 12.1 on CD.

Physlets Resource Page