JEE Main & Advanced Physics NLM, Friction, Circular Motion Question Bank Mock Test - Newtons Laws of Motion With Friction

  • question_answer
    A body of mass \[M\]is kept on a rough horizontal surface (friction coefficient \[\mu \]). A person is trying to pull the body by applying a horizontal force but the body is not moving. The force by the surface on the body is \[F\], where

    A) \[F=mg\]

    B) \[F=\mu Mgf\]

    C) \[Mg\le F\le Mg\sqrt{1+{{\mu }^{2}}}\]

    D) \[Mg\,\ge F\,\ge =\mu Mg\sqrt{1+{{\mu }^{2}}}\]

    Correct Answer: C

    Solution :

    [c] Maximum force by surface when friction works \[\sqrt{{{f}^{2}}+{{R}^{2}}}=\sqrt{{{(\mu R)}^{2}}+{{R}^{2}}}=R\sqrt{{{\mu }^{2}}+1}\] Minimum force = R when there in no friction Hence, ranging from R to \[R\sqrt{{{\mu }^{2}}+1}\]we get, \[mg\le F\le mg\sqrt{{{\mu }^{2}}+1}\]


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