Give two examples of friction:
-being useful in everyday life
-being a problem in everyday life

friction as friend
(1). It is becomes difficult to walk on a slippery road due to low friction. When we move on ice, it  becomes difficult to walk due to low friction of ice
.2. We can not fix nail in the wood or wall if there is no friction. It is friction which holds the nail.
friction as foe
1. The main disadvantage of friction is that it produces heat in various parts of machines. In this way  some useful energy is wasted as heat energy.2. Due to friction we have to exert more power in machines.

Friction is useful when we park our cars. Without friction a car will not stop and remain static. So will our bed, sofa, chairs. They will slide too much and create problems.

We cannot stand properly, walk properly without friction. We will collide with each other every minute.  In winter we rub our hands against each other, we generate heat using friction. that makes us warmer.

Friction dissipates some amount of kinetic energy as heat, radiation and sound. The creeking noise of brakes, old doors comes from friction.  In machines, friction reduces the efficiency of energy used. More effort and energy required to perform some work.  It causes wear and tear of the machines, tyres etc. 

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