Study Materials

NCERT Solutions for Class 8th Science

 

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Chapter 12. Friction

Chapter Review

 

 

 

Chapter review:

  • Friction opposes the relative motion between two surfaces in contact. It acts on both the surfaces.
  • The force of friction always opposes the applied force.
  • Spring balance is a device used for measuring the force acting on an object.
  • Friction can also produce heat. Vigorously rub your palms together for a few minutes.
  • Friction depends on the nature of surfaces in contact.
  • The substances which reduce friction are called lubricants.
  • When one body rolls over the surface of another body, the resistance to its motion is called the rolling friction.
  • When one body slides over the surface of another body, the resistance to its motion is called the sliding friction.
  • Static friction comes into play when we try to move an object at rest.
  • Rolling friction is smaller than the sliding friction.
  • Sliding friction is smaller than static friction.
  • The frictional force exerted by fluids is also called drag.
  • Friction can be increased by making a surface rough.
  • Friction can be reduced by using lubricants.

 

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