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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
A charged glass rod attracts a charged plastic straw.
Define static friction
A body needs a force F1 just to start moving on a surface, a force F2 to continue its motion and a force F3 to roll on the surface. What is
- the static friction
- sliding friction and
- rolling friction? State whether F2 is equal, less than or greater than (1) F1 and (2) F3.
Answer the following in a word or two or in a sentence.
Why does a rolling ball stop after moving some distance?
Fill in the blank.
Weight remaining the same, friction is independent of ............. of surface in contact.
Tick the most appropriate answer.
A car skids on a wet or muddy road due to
Answer the following in a word or two or in a sentence.
Name a method used to reduce friction.
Rolling friction is slightly greater than sliding friction.
Assertion: We can live very happily if friction is not present in nature.
Reason: The airplane shape is streamlined to reduce the effort of frictional force.
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.
