NCERT Solutions for Friction, Class 8 Science Notes Introduction to Friction Class 8 Science: In the fascinating world of physics, one encounters a force that influences our daily lives in countless ways: friction. Imagine a world without the resistance that friction provides: objects sliding uncontrollably, walking becoming a slippery challenge, and machines refusing to function as intended. Friction, in essence, is the force that opposes the motion or the onset of motion between two surfaces in contact. As we delve into the realms of static and kinetic friction, explore the factors that influence this force, and uncover ways to harness or mitigate its effects, we embark on a journey to understand the fundamental principles of friction and its pivotal role in shaping our interactions with the physical world. So, let's peel back the layers and unravel the intriguing science behind friction in this Class 8 exploration. For more information, visit- www.vavaclasses.com

1. CHAPTER 9
FRICTION
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2. Force of friction
• Force of friction is a force which opposes the motion of an object over
a surface.
• Force of friction acts between the object and the surface.
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3. Factors affecting friction
• Friction depends upon two factors
• i) Nature of the surfaces in contact
• ii) How hard the surfaces press together
Friction is less on smooth surfaces Friction is more on rough surface
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4. Friction is more if surface is pressed harder
Friction is less if surfaces are not pressed harder
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5. Cause of friction
Friction is caused due to interlocking of
irregularities between the two surfaces in contact
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6. Type of friction
• Static friction
• Sliding friction
• Rolling friction
• Sliding friction is slightly less than static friction
• Rolling friction is less than static and sliding friction
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7. Friction is necessary
• It is possible to hold the tumbler due to friction between the hand
and the tumbler
• Friction between the feet and the ground help us to walk
• It is possible to write due to friction between the pen and the paper
• Friction between the tyres and the road helps in moving the vehicle
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8. Friction is undesirable
• Soles of shoes wear out due to friction.
• Knives looses their sharp edges due to friction.
• Tyres of vehicles wear out due to friction.
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9. Increasing friction
• Friction can be increased by increasing the roughness of the surface.
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11. Reducing Friction
• Using lubricants like oil and grease
• Using rollers and wheels
• Using ball bearing
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12. Fluid friction
Fluid friction
Fluid friction
Fluid friction
The friction force exerted by liquid and gases on
moving objects is called fluid friction or drag.
Fluid friction depends upon
Speed of object
Shape of the object
Nature of the object
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13. THANK YOU
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