Chapter 12 Friction

  • Push or pull is known as force.
  • Friction is the opposing force which is exerted by a moving body.
  • Friction helps in moving, running and stops the body.
  • Friction is of different types: static friction, rolling, sliding and dynamic.
  • Interlocking of irregularities in two surfaces called as friction.
  • Rolling friction is usually less than sliding friction.
  • Sliding friction is smaller than the static friction.
  • The substance which helps in reducing the friction or make the surface smooth is called as lubricant.
  • When one body rolls over another body, this is called rolling friction.
  • When one body slides over another body is known as sliding friction.
  • Ball bearing are the small balls which are used between hubs and the axles of ceiling fans to reduce the friction.
  • The frictional force exerts by the fluids is known as drag.
  • Aero-plane have such shape to reduce the friction.
  • Friction is more felt on the rough surfaces.
  • Friction depends on the point of contact of two surfaces.
  • Heat is produced by friction.

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Exercise 1 ( Page No. : 156 )