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Variable Inertia Set

Item # 96-1060

Regular price $17.50
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The Variable Inertia Set is simple to set up and a fun activity to study rotational inertia. Students investigate how varying the distribution of mass (steel balls) inside a compartmentalized plastic disc effects how the disc rolls down an inclined plane.

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Other Options

Price Qty for
Visible Variable Inertia Set Visible Variable Inertia Set Item # 96-1010
$19.95 10 $18.80
Exploring Rotational Inertia Classroom Kit Exploring Rotational Inertia Classroom Kit Item # 96-1011

Additional Details

This is a unique lab that is simple to set up and illustrates an abstract concept in an easy-to-understand manner. It consists of two plastic discs in two halves (4 halves total) with the same mass and diameter. The discs are hollow inside with injection molded compartments into which balls are inserted in a variety of configurations. You can place the steel balls (19mm ball size) along the rim of the discs, in the center, or in a straight line across, as illustrated. This effectively varies the distribution of mass to become either "center heavy" or "rim heavy." Quickly change the distribution of mass by loading balls in compartments inside two plastic discs. Which is faster - the disc with the mass toward the center or toward the rim? Why?

Please note: The Inclined Plane is sold separately.

WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information go to


What’s Included

  • Eight 19 mm (0.75") steel spheres
  • One pair of variable inertia disks
  • Two sets of securing hardware


Order Qty Price Qty for Discount Discount Price Total Savings
3/4 3/4" Steel Ball Item # P1-5002
$1.00 50 $0.90