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प्रश्न
Explain how friction can be minimized.
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उत्तर
- Using lubricants:
- A substance, which reduces the frictional force, is called a lubricant. Example: Grease, coconut oil, graphite, castor oil, etc.
- The lubricants fill up the gaps in the irregular surfaces between the bodies in contact. This provides a smooth layer thus preventing direct contact between their rough surfaces.
- Using ball bearing:
Since the rolling friction is smaller than sliding friction, sliding is replaced by rolling with the usage of ball bearings. We can see lead shots in the bearing of a cycle hub.
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संबंधित प्रश्न
Give examples to show that friction is both a friend and a foe.
Write true or false.
Liquids offer more friction than the gases.
Define rolling 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.
Rolling friction is ........... than sliding friction.
Answer the following in a word or two or in a sentence.
Name the force responsible for opposing the motion between two bodies in contact.
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 |
Why is a ball bearing used in a cycle hub?
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.
