Frictional Force

Made By: Anum, Sania and Fatima


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. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. 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 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.

Methods of Reducing Friction

Use of Lubricants: The parts of machine which are moving over one another must be properly lubricated by using oils and lubricants of suitable viscosity.

Use of Grease: Proper greasing between the sliding parts of machine reduces the friction.

Use of Ball Bearing: In machines where possible, sliding friction can be replaced by rolling friction by using ball bearings.

Design Modification: Friction can be reduced by changing the design of fast moving objects. The front of vehicles and airplanes made oblong to minimize friction.

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