Following a discussion of forces, torques, and the conditions for static equilibrium, I tell my introductory mechanics class that I will show them how to measure the coefficient of static friction, μs, between the surfaces of a block and the front bench using nothing but a straightedge. After a few seconds of hushed anticipation, I nudge the block in Fig. 1 (a) gently with the straightedge, applying a horizontal force F that gradually increases from zero to a value that either causes the object to slip (Fs) or to tip (Ft). Which of these happens first depends on μs, the depth D of the block, and on h, the height above the bench surface at which F is applied. Starting at the bottom of the block, it tends to slip before tipping, but there is a critical height hc above which the block tips before slipping. The value of hc at which this transition occurs is then used to produce a value of μs for these surfaces.
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November 2012
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November 01 2012
Slipping and Tipping: Measuring Static Friction with a Straightedge
Eric Dietz;
Eric Dietz
a)
California State University
, Chico, Chico, CA
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Isaac Aguilar
Isaac Aguilar
b)
California State University
, Chico, Chico, CA
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a)
Eric Dietz, Department of Physics, California State University, Chico, Chico, CA 35929; EDietz@csuchico.edu
b)
Isaac Aguilar, Department of Physics, California State University, Chico, Chico, CA 35923; iaguilarparallel@gmail.com
Phys. Teach. 50, 475–476 (2012)
Citation
Eric Dietz, Isaac Aguilar; Slipping and Tipping: Measuring Static Friction with a Straightedge. Phys. Teach. 1 November 2012; 50 (8): 475–476. https://doi.org/10.1119/1.4758147
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