wat r d advantages &disadvantages of friction (4 points atleast)

Advantages of friction:

1. no two bodies will stick to each other if there is no friction.

2. walking will not be possible without friction.

3. brakes of the vehicles will not work without friction.

4. writing on black board or on paper will not possible without friction.

Disadvantages of friction:

1. friction causes wear and tear of tyres of vehicles.

2. due to friction , extra energy hes to be spent in overcoming the friction. thus friction involves unnecessary expense of energy.

3. friction force result in the production of heat, which causes damages to the machinery. 

4. friction cause wear and tear of parts of machinery in contact. thus their life time reduces.