1Q60.35 - Football

Code Number:
1Q60.35
Demo Title:
Football
Condition:
Good
Principle:
Torque & Stable Axis
Area of Study:
Mechanics
Equipment:
Football.
Procedure:

When spun the frictional torques will cause the football to rotate about its statically unstable axis.  In the case of the football, spin it about its short axis and it will eventually stand up on its point.

References:
  • Kenneth Brecher and Rod Cross, "Physics of the PhiTOP®", TPT, Vol. 57, #2, Feb. 2019, p. 74.
  • George Barnes, "Tippy Top Thoughts", TPT, Vol. 25, #4, April 1987, p. 200.
  • Ralph Baierlein, Matthew Treptow and Mike Flynn, "Spinning Footballs and Class Rings", TPT, Vol. 24, #6, Sept. 1986, p. 361.
  • D. Rae Carpenter, Jr., "L'Eggs Demonstrations", TPT, Vol. 15, #3, Mar. 1977, p. 188.
  • George D. Freier, "The Tippy-Top", TPT, Vol. 5, #1, Jan. 1967, p. 36.
  • Peter J. Brancazio, "Rigid-Body Dynamics of a Football", AJP, Vol. 55, #4, Apr. 1987, p. 415.
  • James C. Lauffenburger, "A Large-Scale Demonstration of the Tippe-Top", AJP, Vol. 40, #9, Sept. 1972, p. 1338.
  • Mu-18, Freier and Anderson, A Demonstration Handbook for Physics.
  • M-788, "Stability of Spinning Objects", DICK and RAE Physics Demo Notebook.
  • Tik Liem, "The Spinning Football", Investigation to Science Inquiry, p. 390.
  • The PhiTOP Instructions, Explained.


Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.