Understanding friction, the unavoidable enemy

For machines with mechanical elements, friction is an unavoidable enemy. It is a major source of service failure and can reduce the lifespan of any machinery, from bicycles and cars to airplanes and assembly lines.

Moving furniture in the micro-world

When moving furniture, heavy objects are easier to move if you rotate them while pushing. Many people intuitively do this. An international research team from Konstanz (Germany), Trieste and Milan (Italy) has now investigated ...

Coastal aquaculture can reduce nutrient transport

Coastal aquaculture produces many types of seafood, including fish, shellfish, and aquatic plants. An ongoing challenge, however, is understanding the impact of excessive aquaculture on nutrient levels in the surrounding ...

Group develops world's first DMA for hard materials

Recently, the Li Faxin Research Group of Peking University College of Engineering developed the world's first dynamic mechanical analyzer (DMA) suitable for hard materials (metals, ceramics, etc.). The instrument is based ...

Friction and wear behavior of tungsten alloy balls revealed

Researchers at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) have recently revealed the collective friction and wear behavior of tungsten alloy balls, the important candidate target material ...

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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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