Page 1 - Lesson Notes
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SAI INTERNATIONAL SCHOOL
                                                          Class8
                                                     Lesson notes
                                                   Subject-Physics
                                                       CH-Friction
                                       Subtopic-Friction , a necessary evil

               Friction: A Necessary Evil
               Frictional force plays an important role in our daily life. In some cases, friction is useful
               and we want to keep it but in other cases friction is harmful and we wish to reduce it.
               Examples:
               1.  Friction enables us to walk without slipping but it also causes wear and tear of our
                    shoes.
               2.  Friction enables a car to move on road without skidding but due to friction the tyres
                    of the car wears out gradually.
               3.  Friction is necessary for the working of machine but it also generates heat which
                    may damage the machines. Energy is required to overcome the friction which also
                    leads to wastage of energy.
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