Demonstrations

Central Forces - Ball on Hoop

Code Number :	1D50.49
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: U of Iowa Disclaimer All RIghts Reserved.
Condition :	Excellent
Principle :	Forces Due To Circular Motion
Area of Study :	Mechanics
Equipment :	Ball on hoop chucked into hand drill.
Procedure :	Attach the apparatus to a short table rod with a parallel rod clamp. Slowly rotate the apparatus until the ball swings upward. As you slow the rotation rate, the ball will smoothly move down towards the starting point. The ball will never go over the "equator". NOTE: To get the ball to move initially from its starting point will require a rotation rate greater than 1.6 revolutions per second and then the ball will jump up to fairly high level. That is why it is usually better to start your explanation when the ball is at its highest level and then slow the rotation rate gradually until the ball is back at the rest point.

References

Said Shakerin, "Apparatus for Rotational Motion", TPT, Vol. 33, # 3, Mar. 1995, p. 173.

N. Gauthier, "Rotational Motion on a Hoop", TPT, Vol. 33, # 5, May 1995, p. 262.

Richard V. Mancuso, and Guy A. Schreiber, "An Improved Apparatus for Demonstrating First- and Second-Order Phase Transitions: Ball Bearings on a Rotating Hoop", AJP, Vol. 73, # 4, April 2005, p. 366.

Richard V. Mancuso, "A Working Mechanical Model for First- and Second-Order Phase Transitions and the Cusp Catastrophe", AJP, Vol. 68, # 3, p. 271, March 2000.

Mail Questions and Comments to: Dale Stille