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9th Class Science Work and energy Question Bank Work, Energy and Power

  • question_answer
    A lift is moving downwards with an acceleration equal to the acceleration due to gravity. A body of mass M kept on the floor of the lift is pulled horizontally. If the coefficient of friction is \[\mu \], then the friction resistance offered by the body is

    A)  \[Mg\]                

    B)         \[\mu Mg\]

    C)  \[2\mu Mg\]            

    D)         zero  

    Correct Answer: D

    Solution :

    Frictional resistance\[=\mu R\] For a lift falling freely, reaction\[=m(g-g)=0\] \[\therefore \]  frictional force\[=0\]


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