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Rolling friction, also called friction in rolling motion or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. . In pure rolling motion, there is only one point of contact between the rolling object and the surface at any instant, and this point remains momentarily at rest relative to the surfa
rolling friction. In the case of bodies capable of rolling, there is a particular type of friction, in which the sliding phenomenon, typical of dynamic friction, does not occur, but there is also a force that opposes the motion, which also excludes the case of static friction. This type of friction is called rolling friction.
Contact mechanics is the study of the deformation of solids that touch each other at one or more points. [1] [2] A central distinction in contact mechanics is between stresses acting perpendicular to the contacting bodies' surfaces (known as normal stress) and frictional stresses acting tangentially between the surfaces (shear stress).
Hertz solved the contact problem in the absence of friction, for a simple geometry (curved surfaces with constant radii of curvature). Carter considered the rolling contact between a cylinder and a plane, as described above. A complete analytical solution is provided for the tangential traction.
His first theoretical hypothesis was contradicted by subsequent research, which showed that rolling friction is actually the dominant factor. Moffatt showed that, as time t {\displaystyle t} approaches a particular time t 0 {\displaystyle t_{0}} (which is mathematically a constant of integration ), the viscous dissipation approaches infinity .
Smaller rolling elements are lighter and thus have less momentum, but smaller elements also bend more sharply where they contact the race, causing them to fail more rapidly from fatigue. Maximum rolling-element bearing speeds are often specified in 'nD m ', which is the product of the mean diameter (in mm) and the maximum RPM.
I will also add a citation for the statement that rolling friction "is much smaller than sliding friction...", since that seems to be a point you're challenging. A quick google search finds hundreds of reliable sources that could be cited. Examples: "Rolling friction is much lower than sliding friction." Bharat Bhushan (2002.) Introduction to ...
Kinetic friction, also known as dynamic friction or sliding 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 μ k , and is usually less than the coefficient of static friction for the same materials.