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Author: Nathan Lampson

This lesson will introduce the concept of friction and explain how it can affect forces.

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Friction is the force that two surfaces exert on each other when they rub. Smooth surfaces produce less friction than rough surfaces.  Without friction a moving object might never stop moving.



When a person uses a sled to sled down a snowy hill, the sled is able to move quickly down the hill because there is very little friction between the hill and the sled.  If a person tried to slide down the hill without a sled, friction is what prevents them from gaining speed.



When a marble rolls down a ramp and onto a carpeted floor, the floor and the marble exert a friction force on each other. Over time, the friction force slows the marble down and brings it to a stop.