Exploring Rotational Inertia Classroom Kit

Item # 96-1011

Regular price $135.00
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Challenge students to develop their own understanding of rotational inertia with this unique, easy-to-use classroom kit.

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Give your students an intuitive feel for rotational inertia! Opaque versions of variable inertia disks can act as great question generators. But after the question is asked, lead students to their own conclusions with this only-from-Arbor classroom kit. Let them discover what parameters affect a system's rotational inertia by manipulating the clear disks and included accessories.
Each classroom kit includes enough materials for 6 groups to perform 4 different activities. Students use custom 3D-printed fixed axles to "feel" the difference between steel spheres arrangements and develop a tactile definition of inertia. This simple activity shows studentsthe conceptual similarity betweem linear and rotational inertia but highlights a key difference. The mass can be the same for both disks, but one can have a greater inertia because of distance from the axis. Students perform rotational "collisions" by suspending a rotating disk then dropping another on top and watching the resultant change in rotation speed. Long free-wheeling axles are included as well. The time-tested experiment of racing the disks down an inclined plane can be done as well, but link together two disks of different inertias with the included axle and roll the system down an inclined plane. This extension of the classic inclined plane demo shows how the impact of different inertias by veering off to one side of the ramp.

Products being sold are not toys. They are for Educational / Laboratory use only. They are not for use by children 12 and under.

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What’s Included

  • 12 clear variable inertia disks (6 sets of 2)
  • 48 steel spheres (6 sets of 8)
  • String for rotational inertia “collisions”
  • 6 red and 6 blue custom-designed 3D printed fixed axles
  • 6 stainless steel smooth axles
  • 50 o-rings (approx.)

Features & Specs

  • Disk dimensions: 4.5" diameter, 1" wide
  • Steel spheres: 3/4" diameter
  • Fixed axle: 3" long when assembled
  • Smooth axle: 6" long, 1/8" diameter
  • Roll of string: 25 meters


Order Qty Price Qty for Discount Discount Price Total Savings
4 4" C-Clamp Item # PX-1209
$11.00 20 $10.00
Inclined Plane Inclined Plane Item # P3-3541
$79.00 6 $71.00


Order Qty Price Qty for Discount Discount Price Total Savings
3/4 3/4" Steel Ball Item # P1-5002
$1.00 50 $0.90
No-Stretch Pulley String, 25 meters No-Stretch Pulley String, 25 meters Item # P1-6110
$4.75 50 $4.40
Visible Variable Inertia Set Visible Variable Inertia Set Item # 96-1010
$19.95 10 $18.80