1Q40.22 - Conservation of Angular Momentum - Hoberman Sphere

Large Hoberman
30 inch Hoberman
Code Number:
Demo Title:
Conservation of Angular Momentum - Hoberman Sphere
Conservation of Angular Momentum
Area of Study:
Hoberman Sphere Mobile.

See also 1Q40.22 in Astronomy.

Hang the Hoberman sphere mobile up by the supplied rope in LR1 or LR2.  In LR 70 the mobile will have to be suspended from a cross arm on one of the tables.

Spin the open sphere at about one rotation per second.  Pull on the ring at the bottom of the sphere.  This will collapse the sphere and the rotation rate will go up dramatically.  Centrifugal flattening will also be observed.  See 1D52.10 for an explanation of this.

  • Richard D. Kaufman, "Angular Acceleration Without Torque?", TPT, Vol. 50, #1, Jan. 2012, p. 35.
  • David L. Mott, "Demonstrating Conservation of Angular Momentum", TPT, Vol. 43, #8, Nov. 2005, p. 552.
  • Blane Baker, "Using an Expandable Toy in Discussing Rotational Motion", TPT, Vol. 43, #4, Apr. 2005, p. 247.
  • Robert Johns, "Acceleration Without Force?", TPT, Vol. 41, #3, Mar. 2003, p. 156.
  • Hantao Ji, Steven Balbus, "Angular Momentum Transport in Astrophysics and the Lab", Physics Today, Vol. 66, #8, Aug. 2013, p. 27.

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