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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
Name the two kinds of forces in nature.
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.
Fill in the blank.
Sliding friction and rolling friction are types of .................. friction.
Tick the most appropriate answer.
Force of friction comes into play when a/an
Tick the most appropriate answer.
Friction is offered by
Fill in the blank.
Rolling friction is ........... than sliding friction.
Fill in the blank.
Friction is a type of .................
Why is a ball bearing used in a cycle hub?
Explain how friction can be minimized.
Assertion: Friction always opposes the motion.
Reason: Whenever one surface moves or tries to move over another surface, the force of friction starts acting on the surfaces.
