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प्रश्न
Give three examples to illustrate that friction is a necessary evil.
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उत्तर
The examples to illustrate that friction is a necessary evil are:
- If friction were absent, we would not be able to walk.
- Friction is necessary to burn a matchstick.
- It is due to friction that we can write on board by chalk.
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संबंधित प्रश्न
Select the correct alternative.
Friction is reduced by
List three ways of reducing friction.
Answer the following in detail.
What are the various effects of force? State one example of each.
Fill in the blank.
More the roughness of a surface, greater is the ........................
Fill in the blank.
Weight remaining the same, friction is independent of ............. of surface in contact.
Tick the most appropriate answer.
If you pour some oil onto a floor, the friction would
Match the following.
| Column I | Column II | |
| a) | Static friction | Viscosity |
| b) | Kinetic friction | Least friction |
| c) | Rolling friction | Objects are in motion |
| d) | Friction between the liquid layers | Objects are sliding |
| e) | Sliding friction | Objects are at rest |
Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play
We have two identical metal sheets. One of them is rubbed with sand paper and the other with ordinary paper. The one rubbed with sand paper shines more than the other. Give reason.
Analogy
Objects placed at rest on earth: ______:: Bodies slide over the surface on other body: ______.
