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 ...

'Melting rock' models predict mechanical origins of earthquakes

Engineers at Duke University have devised a model that can predict the early mechanical behaviors and origins of an earthquake in multiple types of rock. The model provides new insights into unobservable phenomena that take ...

Slippery when wet: How does lubrication work?

In a recent paper in Science Advances, researchers from the University of Amsterdam present new experimental insight into how lubrication works. They have developed a new method using fluorescent molecules to directly observe ...

Why is ice so slippery?

The answer lies in a film of water that is generated by friction, one that is far thinner than expected and much more viscous than usual water through its resemblance to the "snow cones" of crushed ice we drink during the ...

How to control friction in topological insulators

Topological insulators are innovative materials that conduct electricity on the surface, but act as insulators on the inside. Physicists at the University of Basel and the Istanbul Technical University have begun investigating ...

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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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