1K10.20 - Ladder Forces

See first paragraph in procedure
See second paragraph in procedure.
Code Number:
1K10.20
Demo Title:
Ladder Forces
Condition:
Good
Principle:
Components of Forces
Area of Study:
Mechanics
Equipment:
Ladder with Rollers on one end, slotted weights and hanger.
Procedure:

Stand the ladder against a wall with the wheels on the wall. Weights may be hung on the various rungs of the ladder to where the ladder starts to slip when set at different angles.  

An interesting version is to make both ends of the ladder frictionless.  When the ladder starts to slide, the top end of the ladder leaves the wall at some point or rotates away from the wall, due to the bottom of the ladder rapidly moving away from the wall. 

References:
  • Daniel Kaplan, "Observing the Forces Involved in Static Friction Under Static Situations",  TPT, Vol. 51, # 4, April 2013, p. 224.
  • Jonathan Bennett, Alex Mauney, "The Static Ladder Problem with Two Sources of Friction", TPT, Vol. 49, # 9, Dec. 2011, p. 567.
  • Yehuda Salu, "Revisiting the Ladder on a Wall Problem", TPT, Vol. 49, # 5, May 2011, p. 289.
  • Mario Belloni, "A Simple Demonstration for the Static Ladder Problem", TPT, Vol. 46, # 8, Nov. 2008, p. 503.
  • Joe Meyer, "Ladder Physics", TPT, Vol. 26, # 8, Nov. 1988, p. 532.
  • Thomas J. Parmley, J. Irvin Swigart and Ray L. Doran, "Lecture Demonstrations for the High School Science Teacher", TPT, Vol. 4, # 1, Jan. 1966, p. 36.
  • "Problem That Bother Me", TPT, Vol. 4, # 3, March 1966, p. 144. 
  • Alejandro G. Gonzalez and Julio Gratton, "Reaction Forces on a Ladder Leaning on a Rough Wall", AJP, Vol. 64, #8, Aug. 1996, p. 1001.
  • Kenneth S. Mendelson, "Statics of a Ladder Leaning Against a Rough Wall", AJP, Vol. 63, # 2, Feb. 1995, p. 148.
  • M. Freeman and P. Palffy-Muhoray, "On Mathematical and Physical Ladders", AJP, Vol. 53, #3, Mar. 1985, p. 276.
  • Mo- 8:  Freier and Anderson,  A Demonstration Handbook for Physics.
  • M- 30:  Richard Manliffe Sutton, Demonstration Experiments in Physics.
  • Robert Ehrlich, "Ladder Against the Wall", Why Toast Lands Jelly-Side Down, p. 60- 63.
  • James Ringlein, "Understanding and Illustrating the atomic origins of friction", APT 72 (7) July 2004, p. 884.


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