{write at least 5 points on each question}
1. why do mountaineers wear shoes with spikes on them ?
2. why is friction said to be necessary evil ?
3. explain the action of ball bearings .
4. why does rough surface offer greater friction than a smooth surface ?
5. what are the advantages of friction ?

Dear Student,

Kindly ask different queries in different thread. Also, refer the solution of second question.

Friction is necessary:

1. To walk, To drive a car, roll.

2. To control speed of vehicles, bouncing balls.

3. To operate screws, blots, harnesses, writing.

4. To have a nature free from violent storms, tsunamis, noise and chaos.

Friction is evil:

1. It wastes a lot of energy, decreases efficiency of vehicles.

2. It generates heat and destroy machines.

3. It leads to rashes to your skin when we fall.

4. All forms of motion in contact with other bodies needs a constant force and thus work is done at every step.

5. For physicists it increases the complexity of calculations.