Friction is what causes fire come start as soon as you rub two sticks together, as these warriors from a Masai tribe in Kenya room doing. (Image credit: Paul Banton / Shutterstock.com)

Friction is the resistance to movement of one object relocating relative to another. It is no a fundamental force, like gravity or electromagnetism. Instead, scientists think it is the result of the electromagnetic attraction in between charged particles in two poignant surfaces.

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Scientists began piecing with each other the regulations governing friction in the 1400s, but because the interactions room so complex, characterizing the force of friction in different instances typically needs experiments and can"t be derived from equations or regulations alone.

For every basic rule around friction, over there are simply as many exceptions. Because that instance, when two stormy surfaces (such together sandpaper) rubbing versus each other periodically have more friction, really smoothly polished materials (such together plates of glass) that have actually been carefully cleaned the all surface ar particles may actually stick to every other an extremely strongly.

species of friction

There are two main types of friction, revolution friction and also kinetic friction. Revolution friction operates in between two surfaces that aren"t moving relative to each other, if kinetic friction acts between objects in motion.


In liquids, friction is the resistance in between moving class of a fluid, i beg your pardon is likewise known together viscosity. In general, more viscous fluids space thicker, so love husband has an ext fluid friction 보다 water.


The atoms inside a hard material deserve to experience friction as well. For instance, if a solid block of steel gets compressed, all the atoms within the product move, creating internal friction.

In nature, there are no completely frictionless environments: also in deep space, small particles of issue may interact, leading to friction.

Coefficient of friction

Two heavy objects moving against each other experience kinetic friction. In this case, the friction is some fraction of the perpendicular force acting in between two objects (the portion is determined by a number dubbed the coefficient the friction, i beg your pardon is established through experiments). In general, the pressure is elevation of the contact area and also doesn"t count on how quick the 2 objects are moving.


Friction likewise acts in stationary objects. Revolution friction avoids objects native moving and is generally greater than the frictional pressure experienced by the exact same two objects once they are relocating relative to every other. Revolution friction is what keeps a box on an incline from slide to the bottom.

Applications of friction

Friction plays vital part in countless everyday processes. Because that instance, when two objects rub together, friction reasons some that the energy of activity to be converted into heat. This is why rubbing two sticks together will eventually produce a fire.

Friction is additionally responsible for the wear and tear on cycle gears and other mechanically parts. That"s why lubricants, or liquids, are often used to mitigate the friction — and also wear and also tear — between moving parts.

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Tia Ghose
Assistant regulating Editor
Tia is the assistant regulating editor and also was formerly a senior writer because that Live Science. Her job-related has showed up in clinical American, Wired.com and other outlets. She holds a master"s in bioengineering from the university of Washington, a graduate certificate in scientific research writing indigenous UC Santa Cruz and a bachelor"s in mechanical engineering from the college of Texas at Austin. Tia was component of a team at the Milwaukee newspaper Sentinel that released the empty Cradles collection on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.