Friction Force : is the force resisting the relative motion of two surfaces in contact .
There are Two Types of Friction :
Static Friction :
Static friction is friction between two objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface. The coefficient of static friction, typically denoted as ?s, is usually higher than the coefficient of kinetic friction.
?S : Coefficient of Friction .
FS : Friction force .
N : Normal force .
Kinetic Friction :
Kinetic (or dynamic) friction occurs when two objects are moving relative to each other and rub together (like a sled on the ground). The coefficient of kinetic friction is typically denoted as ?k, and is usually less than the coefficient of static friction.
?k : Coefficient of Kinetic Friction .
Coefficient of Friction :
(also known as the frictional coefficient) is a dimensionless scalar value which describes the ratio of the force of friction between two bodies and the force pressing them together. The coefficient of friction depends on the materials used; for example, ice on steel has a low coefficient of friction (the two materials slide past each other easily), while rubber on pavement has a high coefficient of friction (the materials do not slide past each other easily). Coefficients of friction range from near zero to greater than one –under good conditions
Lecture 7
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The coefficient of friction is a dimensionless quantity symbolized by the Greek letter( ? ) and is used to approximate the force of friction. Friction can be viewed, again as an approximation, as being of two primary types, static or kinetic. The coefficient of static friction is defined as the ratio of the maximum static friction force (F) between the surfaces in contact to the normal (N) force. The coefficient of kinetic friction is defined as the ratio of the kinetic friction force (F) between the surfaces in contact to the normal force:
Both static and kinetic coefficients of friction depend on the pair of surfaces in contact; their values are usually approximately determined experimentally. For a given pair of surfaces, the coefficient of static friction is usually larger than that of kinetic friction; in some sets the two coefficients are equal, such as Teflon?on?Teflon.
Angle of friction ( ? ) :
The angle of friction for two surfaces in contact is defined as the angle that the maximum contact force makes with the direction of normal force .
? = tan(? )
? = tan-1 (?)
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
الرجوع الى لوحة التحكم
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