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प्रश्न
List three ways of reducing friction.
उत्तर
Ways to reduce friction:
- Providing ball bearings or wheels between the moving parts of the machine or vehicles reduces friction and allow smooth movement as rolling friction is less than sliding friction.
- Oiling or lubricating (with graphite or grease) the moving parts of a machine reduces friction. Fine powder like talcum powder also works as a lubricant to reduce friction.
- Polishing the rough surface reduces friction offered by it.
- Streamlining (giving special shape to experience minimum drag) the bodies of aeroplanes, cars, boats, and ships help reduce drag (fluid friction) while travelling through air or water.
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संबंधित प्रश्न
When a glass rod is rubbed with a piece of silk cloth the rod ______.
Fill in the blank.
We use ball bearings to .................. the friction.
Fill in the blank.
More the roughness of a surface, greater is the ........................
Fill in the blank.
Friction depends upon the ............... of an object.
Answer the following in short.
List the various states of matter that offer frictional force?
A moving body comes to rest due to friction alone.
Complete the analogy.
Knot in a thread : _____ friction : : Ball bearing : _____ friction
Analogy
Objects placed at rest on earth: ______:: Bodies slide over the surface on other body: ______.
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.
