# NCERT VIII - Sciences Give examples to show that friction is both a friend and a foe.

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by lalKunda

2015-04-01T21:42:25+05:30

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Friction as friend:
- We need friction to walk on the floor
- the wheels of vehicles need friction to roll on the roads
- friction is needed while climbing a tree

Friction as foe:
- friction between parts of machines decreases their efficiency
- it produces a lot of noise and wastes energy
- The life of machines is degraded.
2015-04-03T01:03:45+05:30

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Friction is a good friend:
Due to friction between the floor/road and our feet/foot wear, we are able to start walking and then stop walking.  Otherwise, when there is no friction, it would be like walking on slippery ice surface.

Without friction all vehicles would skid.  Without friction, the things we hold in hands, will slip through and fall down.  Without good amount of friction, it will be very difficult to climb mountains.

Friction is not so good as:
But friction, takes away energy from moving vehicles. We need to overcome friction to work, to make machines work.  Due to friction machine parts get heated up, and get  worn out.  Without friction, the ceiling fans would not stop after being switched off.  Due to friction, we are unable to move easily heavy object like sofas, cupboards, tables in our houses.

We need to exert a lot of force.  Due to friction the surfaces get scratches.  When there is a lot of  friction, there is sound (screeching, shrill sounds) generated that is painful to the ears.

Friction is desirable, but in small quantities only.