Limiting coefficient of static friction - Revision history

Vipul: /* Range of values */

2010-01-20T21:48:29Z

Range of values

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	The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.		The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.

	~~Some experimentally determined values are~~:		{{#lst:table of friction coefficients\|table}}

	~~See [[~~table of friction coefficients~~]].~~

	==Subtleties==		==Subtleties==

Vipul at 21:24, 20 January 2010

2010-01-20T21:24:59Z

← Older revision		Revision as of 21:24, 20 January 2010
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	The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].		The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].

			The angle <math>\theta</math> defined as <math>\tan^{-1}(\mu_s)</math> is termed the [[angle of friction]].

	==Units and dimensions==		==Units and dimensions==
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	The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.		The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.

			Some experimentally determined values are:

			See [[table of friction coefficients]].

	==Subtleties==		==Subtleties==

Vipul at 21:07, 20 January 2010

2010-01-20T21:07:12Z

← Older revision		Revision as of 21:07, 20 January 2010
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	==Definition==		==Definition==

	Given two surfaces, the '''limiting coefficient of static friction''' between them, denoted <math>\mu_s</math> or <math>\mu_l</math>, is defined as the number such that the [[static friction]] between any two bodies with these two surfaces respectively as the surfaces of contact cannot exceed <math>\mu_sN</math>, where <math>N</math> is the [[normal force]] between the two bodies.		Given two surfaces, the '''limiting coefficient of static friction''' (also called the '''coefficient of static friction''' or '''static friction coefficient''') between them, denoted <math>\mu_s</math> or <math>\mu_l</math>, is defined as the number such that the [[static friction]] between any two bodies with these two surfaces respectively as the surfaces of contact cannot exceed <math>\mu_sN</math>, where <math>N</math> is the [[normal force]] between the two bodies.

			For a block resting on a table, the limiting coefficient of static friction between the lower surface of the block and the upper surface of the table is defined as the maximum possible ratio of an applied horizontal force to normal force for which the block does not slip against the table.

	The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].		The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].
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	The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.		The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.

			==Subtleties==

			===Coefficient of static friction makes sense only for uniform surface of contact===

			The coefficient of static friction makes sense only when the nature of the contact surfaces is uniform throughout the area of contact. If the surface is nonuniform, different parts of the surface may yield different contributions. In this case, the maximum possible value of static friction depends not only on the total value of the normal force but also on the way the normal force is distributed over the surface of contact. If <math>P</math> is the pressure, then:

			<math>N = \int P \, dA</math>

			and the maximum permissible static friction force is:

			<math>f_s = \int \mu_s P \, dA</math>
	==External links==		==External links==

Vipul: /* Constitutive factors and measurement */

2010-01-19T02:12:04Z

Constitutive factors and measurement

← Older revision		Revision as of 02:12, 19 January 2010
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	==Constitutive factors and measurement==		==Constitutive factors and measurement==

	The limiting coefficient of static friction between two surfaces depends on the two surfaces, and as such, should be the same for the same pair of surfaces. However, the coefficient depends on a number of factors ~~such as dampness, scratches, or minor surface changes, hence the measurement for the same pair of surfaces may differ with time.~~		===Constitutive factors===

			The limiting coefficient of static friction between two surfaces depends on the two surfaces, and as such, should be the same for the same pair of surfaces. However, the coefficient depends on a number of factors such as dampness, adherence of dust to the surfaces, scratches, or minor surface changes, hence the measurement for the same pair of surfaces may differ with time.

			===Directional dependence===

			The limiting coefficient of static friction may vary somewhat with direction if the surfaces themselves are not isotropic, i.e., they appear different in different directions. The microscopic corrugations of surfaces such as wood may be different in different directions.

			===Empirical measurement===
	For this reason, the limiting coefficient of static friction for a pair of surfaces must be determined empirically, through measurement. However, a reasonable approximate value can be estimated based on the nature of the surfaces.		For this reason, the limiting coefficient of static friction for a pair of surfaces must be determined empirically, through measurement. However, a reasonable approximate value can be estimated based on the nature of the surfaces.

			==Coefficient of static friction for composite of surfaces==

			Because the surfaces may be non-uniform, the limiting coefficient of static friction may be different for different parts of the surface. In this case, there is no single choice of an ''average'' limiting coefficient of static friction. Rather, the limiting value of static friction that can be applied also depends on how the normal force is distributed across the different parts of the surface. If <math>P</math> denotes the pressure, then the limiting value of static friction is the integral over area elements:

			<math>\int \mu_s(A) P \, dA</math>

	==Range of values==		==Range of values==

Vipul at 01:21, 19 January 2010

2010-01-19T01:21:05Z

← Older revision		Revision as of 01:21, 19 January 2010
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	The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.		The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.

			==External links==

			===Instructional video links===

			* [http://www.youtube.com/watch?v=ErsbmryQlX8 coefficient of static friction (video on Youtube)]

Vipul at 00:36, 17 January 2010

2010-01-17T00:36:42Z

← Older revision		Revision as of 00:36, 17 January 2010
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	The limiting coefficient of static friction is a dimensionless scalar and does not need units.		The limiting coefficient of static friction is a dimensionless scalar and does not need units.

			==Constitutive factors and measurement==

			The limiting coefficient of static friction between two surfaces depends on the two surfaces, and as such, should be the same for the same pair of surfaces. However, the coefficient depends on a number of factors such as dampness, scratches, or minor surface changes, hence the measurement for the same pair of surfaces may differ with time.

			For this reason, the limiting coefficient of static friction for a pair of surfaces must be determined empirically, through measurement. However, a reasonable approximate value can be estimated based on the nature of the surfaces.

	==Range of values==		==Range of values==

	The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.		The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.

	~~==Measurement==~~

	The limiting coefficient of static friction must be determined empirically, though measurement. Because a lot depends on the specific surfaces, the measurement may vary due to factors such as dampness, scratches, or minor changes to the surface.

Vipul at 17:42, 22 November 2009

2009-11-22T17:42:27Z

← Older revision		Revision as of 17:42, 22 November 2009
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			{{constitutive coefficient}}

	==Definition==		==Definition==

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	The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].		The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].

			==Units and dimensions==

			The limiting coefficient of static friction is a dimensionless scalar and does not need units.

			==Range of values==

			The limiting coefficient of static friction typically takes values in the range of <math>0.2</math> to <math>0.6</math>. In most cases, the limiting coefficient of static friction is less than <math>1</math>, but there could be situations where it is greater than <math>1</math>. For very slippery surfaces, the limiting coefficient of static friction may be less than <math>0.1</math>.

			==Measurement==

			The limiting coefficient of static friction must be determined empirically, though measurement. Because a lot depends on the specific surfaces, the measurement may vary due to factors such as dampness, scratches, or minor changes to the surface.

Vipul: Created page with '==Definition== Given two surfaces, the '''limiting coefficient of static friction''' between them, denoted $\mu_s$ or $\mu_l$ , is defined as the number suc…'

2009-11-22T15:25:50Z

Created page with '==Definition== Given two surfaces, the '''limiting coefficient of static friction''' between them, denoted <math>\mu_s</math> or <math>\mu_l</math>, is defined as the number suc…'

New page

==Definition==

Given two surfaces, the '''limiting coefficient of static friction''' between them, denoted <math>\mu_s</math> or <math>\mu_l</math>, is defined as the number such that the [[static friction]] between any two bodies with these two surfaces respectively as the surfaces of contact cannot exceed <math>\mu_sN</math>, where <math>N</math> is the [[normal force]] between the two bodies.

The notion of limiting coefficient of static friction arises as part of the [[Coulomb model of friction]].