Dark Matter and Uniform Circular Motion

Students explore the discovery of dark matter by completing a lab on uniform circular motion to investigate how variables such as mass and radius affect the orbital speed of an object. With the relation they derive, students can calculate the value of an unknown mass. This method is very similar to how astronomers measure the speeds of stars in galaxies, providing some of the most compelling evidence for dark matter.


  • Lesson plans: Dark Matter and Uniform Circular Motion
  • Videos: The Mystery of Dark Matter (approx. 30 min)
  • Activities: Dark Matter Lab - Measuring Mass Using Circular Motion (worksheet, solutions, and teacher's notes)
  • Supplementary Materials: Dark Matter in a Nutshell and more
  • Teacher-provided Materials: Centripetal motion apparatus (string, rubber stopper, washers, plastic tube, paper clip)

(Note: all lesson plans and worksheets provided as PDFs and modifiable MS Word documents)

Intended Audience: Senior High (Gr 11-12)
Lesson Topics: Astronomy, Circular Motion, Gravity
Price: Free