Friction


 
 
Concept Explanation
 

Friction

Two bodies placed in contact can exert forces parallel to the surfaces in contact. Force acting between the surfaces of two objects is called the force of friction. Force of friction always acts in the opposite direction of the movement of object. Force of friction is acting over all the moving objects. For example:

1. A moving ball stops after going to a certain distance. This happens because of force of friction between the surface of ground and the surface of ball.

2. A moving boat stops after some distance because of friction between the surface of water and the surface of boat.

Since force of friction comes into action only after interaction between two objects, thus, it is a type of contact force.

  • Friction also causes heat. When surfaces are rubbed together, heat is produced. Due to friction the surface of objects weared away. The bottom of your shoes, type of the vehicle becomes smooth due to wearing. Friction helps us in walking. When we walk, there is friction between our foot (sole of our shoe) and the ground. This prevents us from slipping.
  • Friction helps us to write. There is friction between the pen and paper on which we are writing.
  • Friction can be increased by making the surface rough. It can be decreased by making the surface smooth or by oiling the surface.
  • Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    A man sharpens his knife  which of  the following properties of friction are in use?

    (i) Friction helps us to hold objects.

    (ii) Friction acts in the opposite direction of motion.

    (iii) Friction causes the surface in contact to wear away.

    (iv) Friction produces heat energy.

    Right Option : D
    View Explanation
    Explanation
    Question : 2

    Treading of tire is done to _________________.

    Right Option : A
    View Explanation
    Explanation
    Question : 3

    When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is such that is acts _______________ .

     

    Right Option : C
    View Explanation
    Explanation
     
     
     


    Students / Parents Reviews [20]