Topic: Frictional Force


Friction is a force that resists the motion of an object that is in contact with another object or material. This force opposes the relative motion between two surfaces that are in contact.


Try and move your Hand over your desk. Now move it in air, which one is easier? Or in which do you use less force? It will be noticed that your hand has contact with your desk therefore; its motion is more difficult than when in the air where there is no contact with your hand.

Advantages of Friction

  1. Walking (locomotion): It is difficult to walk on slippery ground floor, the friction on it is very small. Therefore, one can walk on the ground easily because there is friction between one’s feet and the ground. Smooth surfaces such as a tiled polished floor and plastic carpets are slippery because of low friction. Rough surfaces like rough cement floors have high frictional force and hence ate not slippery. They are easy to walk on. Compare the movement of a car on wet slippery road and on a dry road.
  2. Friction belt: It is easy to derive a mechanism with the help of friction between the belt and the part of machine affected. For example, the friction that exists between the fan belt and fan allows the fan to operate in order to cool the radiator of a car.
  3. Grindstone: A cutlass, knife or any other sharp edge can be sharpened by the use of a grindstone. The friction between the grindstone and these tools will allow the tools to be sharpened. Another example of this is a file used to smoothen or cut through hard surfaces. The file can operate by the use of friction.
  4. Ladder: A ladder positioned against a vertical wall will not slide because of the friction between the floor on which it stands and the foot of the ladder.
  5. Tyre: The grip of the tyre on the road allows a car to move without skidding and this is caused by the friction between the tyre and the road
  6. Brake: Friction between the brake drum and the brake lining of an automobile brings the automobile to a halt when they come in contact.
  7. Bolt and nut: Two pieces of metal can stay together when bolts and nuts are used because of the friction built up between the bolts and nuts when they are tightened. The same principle applies to two pieces of wood which can be held together by nails, the friction between the nail and the pieces of wood allows for that.

Disadvantages of Friction

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