8th Class Science Sample Paper Science Sample Paper-3

  • question_answer                                    Discuss the various ways to reduce the friction.


    Friction may be reduced in the following ways :
    (i) Polishing the surface: We polish the rubbing surfaces to reduce their unevenness and make them smooth.                                                                                            
    (ii) Lubricating the surface: To reduce friction in order to increase efficiency, when oil, grease or graphite is applied between the moving parts of a machine, a thin layer is formed there and moving surfaces do not directly rub against each other. These substances are lubricants which reduce the friction.                                                      
    (iii) Using wheels and ball bearings: By using wheels and ball bearing, we convert sliding friction into rolling friction. This reduces friction between the two contact surfaces and helps us to save energy, effort and time.            
    (iv) Streamlining: Objects are given special shapes, such as streamlined body to aeroplanes. Their bodies? shapes make them lose less energy in overcoming friction. Hence, all vehicles are designed to have shapes that reduce fluid friction.


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