Demonstrations

Meniscus - Stable Equilibrium

Code Number :	2A20.45
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: University of Iowa Disclaimer All Rights Reserved..
Condition :	Excellent
Principle :	Concave vs. Convex Meniscus
Area of Study :	Heat & Fluids
Equipment :	9" evaporating dish, ping pong balls.
Procedure :	Start with the evaporating dish and water. The water should come to about 1" from the top of the evaporating dish to start the experiment. Add 1 to 3 ping pong balls and notice that they will quickly migrate to the sides of the dish (Concave meniscus). Adding more water to the evaporating dish until the dish is overfull will cause the ping pong balls to migrate to the center of the dish (Convex meniscus).

References

Wojciech Dindorf, "Stable Equilibrium at the Top of a Hill," TPT, Vol. 40, # 2, p. 116, (Feb. 2002).

Harold J. Teague, "Position of Objects Floating in a Glass," TPT, Vol. 36, # 7, p. 410, (Oct. 1998).

Martin Gardner, "Two Corking Good Challenges", TPT, Vol. 31, # 8, Nov. 1993, p. 477.

Yves Pomeau and Emmanuel Villermaux, "Two Hundred Years of Capillarity Research", Physics Today, March 2006, p. 39.

George B. Barne, "Divergent Barroom Physics, TPT, Vol. 14, # 1, January 1976, page 41.

James T. Schreiber, "Barroom Physics, Part II", TPT, Vol. 13, # 7, Oct. 1975, p. 418.

Richard A. Marble, "Floating Objects", TPT, Vol. 10, # 2, Feb. 1972, p. 67.

Mail Questions and Comments to: Dale Stille