Modeling the friction between pages in a book

It all started with a shaky washing machine. Pedro Reis, head of the Flexible Structures Laboratory at EPFL's School of Engineering, rolled up a piece of fabric and placed it under the machine to stop it from moving. After ...

3-D images of fabric 'sandwich' can help measure textile friction

To quantify exactly how itchy a wool sweater might be when worn directly against the skin, or how soft a blanket spread on your bed can be, North Carolina State University researchers developed a method of measuring fabric's ...

Aerodynamicists reveal link between fish scales and aircraft drag

The team's findings have been published in Nature: Scientific Reports: "Transition delay using biomimetic fish scale arrays," and in the Journal of Experimental Biology: "Streak formation in flow over biomimetic fish scale ...

Exponential scaling of frictional forces in cells

AMOLF researchers have presented a theory that describes the friction between biological filaments that are crosslinked by proteins. Surprisingly, their theory predicts that the friction force scales highly nonlinearly with ...

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Friction

Friction is the force resisting the relative lateral (tangential) motion of solid surfaces, fluid layers, or material elements in contact. It is usually subdivided into several varieties:

Friction is not a fundamental force, as it is derived from electromagnetic force between charged particles, including electrons, protons, atoms, and molecules, and so cannot be calculated from first principles, but instead must be found empirically. When contacting surfaces move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy, or heat. Contrary to earlier explanations, kinetic friction is now understood not to be caused by surface roughness but by chemical bonding between the surfaces. Surface roughness and contact area, however, do affect kinetic friction for micro- and nano-scale objects where surface area forces dominate inertial forces.

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