JEE Main & Advanced Physics NLM, Friction, Circular Motion JEE PYQ - NLM Friction Circular Motion

  • question_answer
    A smooth block is released at rest on a\[45{}^\circ \]incline and then slides a distance d. The time taken to slide is n times as much to slide on rough incline than on a smooth incline. The coefficient of friction is               [AIEEE 2005]

    A) \[{{\mu }_{k}}=1-\frac{1}{{{n}^{2}}}\]

    B) \[{{\mu }_{k}}=\sqrt{1-\frac{1}{{{n}^{2}}}}\]

    C) \[{{\mu }_{s}}=1-\frac{1}{{{n}^{2}}}\]

    D) \[{{\mu }_{s}}=\sqrt{1-\frac{1}{{{n}^{2}}}}\]

    Correct Answer: A

    Solution :

    [a] The situation is shown in figure when friction is absent,
    When friction is present 
    From Eqs. (i) and (ii), we get
    (given in question)
    or         or

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