PDF chapter test TRY NOW

Let us understand the factors affecting friction by considering an activity.
  • Tie a string around a brick.
  • Pull the brick by using a spring balance(We apply force by pulling the spring balance).
  • Note down the spring balance reading when the brick begins to move.
It gives the amount of force of friction between the floor and the surface of the brick.

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For a difference, repeat this activity by wrapping a bit of jute bag around the brick. Pull the brick by a spring balance and note down the spring balance reading when the brick begins to move. Finally, wrap a bit of polyethene around the brick and repeat the activity.
 
Thus, frictional force depends on the surfaces which are in contact. It is difficult to move an object on a rough surface because of high friction, whereas it is very easy to move the object on a smooth surface due to less friction.
 
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Tile floor
 
The surface of the tile floor is very smooth, so friction is very less. That is why we feel slippery when it is wet.
 
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Rough floor
 
The surface of the floor is very rough, so friction is very high. Therefore, we can walk easily on the rough floor even though it is wet.
What is a spring balance?
Spring balance is a device that is used for measuring the force acting on an object. It consists of a coiled spring that gets stretched once a force is applied to it. Stretching of the spring is measured by a moving pointer on a graduated scale. The reading on the scale provides the magnitude of the force.
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Spring balance