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प्रश्न
Give three examples to illustrate that friction is a necessary evil.
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
Name the two kinds of forces in nature.
State two factors which directly affect the force of friction.
Answer the following in short.
Define force. Write its SI unit.
Fill in the blank.
Smoother the surface, ................. is the frictional force offered by it.
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 |
Explain how friction can be minimized.
In figure, a boy is shown pushing the box from right to left. The force of friction will act on the box
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.
Assertion: There is a danger of a vehicle skidding on a wet road.
Reason: The tires of the vehicle lose their grip on the road due to an increase in friction due to the presence of water on the road.
