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ERIC Number: EJ1000736
Record Type: Journal
Publication Date: 2012-Nov
Pages: 2
Abstractor: As Provided
Reference Count: 1
ISSN: ISSN-0031-921X
Slipping and Tipping: Measuring Static Friction with a Straightedge
Dietz, Eric; Aguilar, Isaac
Physics Teacher, v50 n8 p475-476 Nov 2012
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, us, 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 (F[subscript s]) or to tip (F[subscript t]). Which of these happens first depends on [mu][subscript s], 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 "h"[subscript c] above which the block tips before slipping. The value of "h"[subscript c] at which this transition occurs is then used to produce a value of [mu][subscript s] for these surfaces. (Contains 1 table and 1 figure.)
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A