person holding a meter stick with two fingers far apart
person holding a meter stick with two fingers together

 

Code Number: 1J10.30

Demo Title: Meter Stick on Fingers

Condition: Good

Principle: Center of Mass

Area of Study: Mechanics

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.
University of Maryland Physics Department QOTW Question #23
University of Maryland Physics Department QOTW Answer #23
1J10.30 - Meter Stick on Fingers
1J10.30 - Meter Stick on Fingers

1J10.30 - University of Maryland QOTW #23