String with Sand filled bottle

 

Code Number: 1K20.70

Demo Title: Falling Bottle Capstan

Condition: Good

Principle: Friction, Simple Harmonic Motion

Area of Study: Mechanics

Equipment:

 String with Sand filled bottle on one end and #6 stopper on the other (Capstan App).

Procedure:

Hang the apparatus over a horizontal rod in an Atwood's arrangement and show that the sand filled bottle is much heavier than the stopper.   Then pull the sand filled bottle close to the rod by pulling on the stopper.  Lift the stopper to an angle of 15 to 20 degrees above the horizontal rod. When you let go of the stopper, the bottle will fall about 1/2 to 2/3's the length of the string before it is stopped by the wrapping action of the stopper around the horizontal rod.

References:

  • Ralph McGrew, "A Simple Mechanical Experiment on Exponential Growth", TPT, Vol. 53, # 4, April 2015, p. 222.
  • Michael Vollmer, Klaus-Peter Mollmann, "Ring Falling into a Chain: No Magic - Just Physics", TPT, Vol. 49, # 6, Sept. 2011, p. 335.
  • Wen-Tang Lee, Huang-Wen Hsiao, "Tension of a Soft Spring in Contact with a Cylinder", TPT, Vol. 47, # 9, December 2009, p. 596.
  • Martin Gardner, "The Falling Keys", TPT, Vol. 28, # 6, Sept. 1990, p. 390.
  • James R. Klein, "Wrapping Around a Pole", TPT, Vol. 16, # 9, Dec. 1978, p. 640.
  • Paul G Hewitt, "Not a Wrap- Around", TPT, Vol. 17, # 4, Apr. 1979, p. 224.
  • R. E. J. Sears, "Comment on 'A Surprising Mechanics Demonstration,' By A. R. Marlow", AJP, Vol. 63, # 9, Sep. 1995, p. 854.
  • David J. Griffiths, Tyler A. Abbott, "Comment on 'A Surprising Mechanics Demonstration,' by A. R. Marlow", AJP, Vol. 60, # 10, Oct. 1992, p. 951.
  • A. R. Marlow, "A Surprising Mechanics Demonstration", AJP, Vol. 59, # 10, Oct. 1991, p. 951.
  • Eugene Levin, "Friction Experiments with a Capstan", AJP, Vol. 59, #1, Jan. 1991, p. 80.
  • Clifford Bettis, "Capstan Experiment", AJP, Vol. 49, #11, Nov. 1981, p. 1080.
  • Martin Gardner, "The Falling Keys", Science Tricks, p. 34.
  • Jearl Walker, "1.178, Hanging Goblet, Ready to Crash", The Flying Circus of Physics Ed. 2, p. 78.
  • Robert Ehrlich,  "The Matchbook and the Keys",  Why Toast Lands Jelly-Side Down, p. 74.
University of Maryland Physics Department QOTW Question #30
University of Maryland Physics Department QOTW Answer #30
1K20.70 - Falling Bottle Capstan
1K20.70 - University of Maryland QOTW #30