1J10.30 - Meter Stick on Fingers

Code Number:
1J10.30
Demo Title:
Meter Stick on Fingers
Condition:
Good
Principle:
Center of Mass
Area of Study:
Mechanics

Disclaimer

Equipment:
Meter Stick, Meter Stick with Hole in the End, and 160g Hanging Weight.
Procedure:

Position fingers anywhere under meter stick and as you slide your fingers together they will always meet at the center of mass.

A variation of this is to hang a weight from one end of the meter stick. In our case if we hang 160 g on the end the demonstration will perform the same except now the equilibrium point is at 25cm.

References:
  • "Correction to: 'Simulation of the Physics Flight,' Phys Teac. 51, 2 42 (April 2013)", TPT, Vol. 52, #5, May 2014, p. 261.
  • Nuri Balta, "Locating the Center of Gravity: The Dance of Normal and Frictional Forces", TPT, Vol. 50, #8, Nov. 2012, p. 456.
  • Said Shakerin, "A Modified Ruler Experimental Apparatus", TPT, Vol. 34, # 2, Feb. 1996, p. 82.
  • Martin Gardner, "Physics Trick of the Month - Curious Feedbacks", TPT, Vol. 32, #1, Jan. 1994, p. 59.
  • Richard V. Mancuso,  "Quantitative Analysis of Moving Two Fingers Under a Meterstick",  TPT, Vol. 31, #4, Apr. 1993, p. 222.
  • Mario Iona m "But the Meterstick Has Mass", TPT, Vol. 31, #6, Sept. 1993, p. 327.
  • Ian Thomas, "Fore!", TPT, Vol. 31, #6, Sept. 1993, p. 327.
  • Joseph L. Spradley, "Meter - Stick Mechanics", TPT, Vol. 28, #5, May 1990, p. 312.
  • M-478: "Stick on 2 Fingers - Unbal. Bar", DICK and RAE Physics Demo Notebook.
  • Robert Ehrlich, "D.9, Moving Two Fingers Under a Meterstick", Turn the World Inside Out, p. 49.
  • Robert Ehrlich, "D.2, Stability of a Floating Object", Turn the World Inside Out, p. 39.
  • Martin Gardner, "Curious Feedbacks", Science Tricks, p. 50.
  • Martin Gardner, "Balancing a Book", Science Tricks, p. 48.
  • Martin Gardner, "28, A Yardstick Question", Smart Science Tricks, p. 46.
  • Martin Gardner, "Feedback by the Yard", Entertaining Science Experiments with Everyday Objects, p. 91.
  • Vicki Cobb and Kathy Darling, "Evenhandedness", Bet You Can't!, p. 107.
  • Borislaw Bilash II and David Maiullo, "Where's the Center?", A Demo a Day: A Year of Physics Demonstrations, p. 150.
  • Jearl Walker, "1.172, Sliding a Stick Across Fingers", The Flying Circus of Physics Ed. 2, p. 77.
  • Charles Taylor, "1.23", The Art and Science of Lecture Demonstration, p. 47.
  • Christopher P. Jargodzki and Franklin Potter, "223, Magic Fingers", Mad About Physics, p. 88, 225.
  • Julius Sumner Miller, Q18 & A18, Millergrams I – Some Enchanting Questions for Enquiring Minds, p. 23 & 82.
PDF icon University of Maryland Physics Department QOTW Question #23
PDF icon University of Maryland Physics Department QOTW Answer #23



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.