Friction

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: Dry friction resists relative lateral motion of two solid surfaces in contact. Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.

Types of Friction

Dry Friction

Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the electromagnetic attraction between charged particles in two touching surfaces.

Fluid Friction

Fluid friction occurs between fluid layers that are moving relative to each other. This internal resistance to flow is named viscosity. In everyday terms, the viscosity of a fluid is described as its "thickness".

Lubricated Friction

Lubricated friction or lubrication is an aspect of fluid friction where a lubricant fluid separates two solid surfaces. Lubrication is a technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load (pressure generated) between the opposing surfaces.

Skin Friction

Skin friction arises from the friction of fluid layers moving against each other within the boundary layer over a body. It is a component of drag in the case of a fluid (such as air) moving past an object, such as an airplane wing or the body of a car.

Internal Friction

Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation. It is caused by the frictional resistance between the particles of a body, and it increases with the hardness of the material.

See Also

• Friction welding
• Friction stir welding
• Friction tape
• Friction loss
• Friction drive
• Friction modifier

This article is a medical stub. You can help WikiMD by expanding it!
Most recent articles Ongoing trials	Wikipedia

Friction

• 

  Friction Animation 2 Blocks

• 

  Friction between surfaces

• 

  Heat by friction

• 

  Free body diagram 2

• 

  Static kinetic friction vs time

• 

  Free body