NEET Sample Paper NEET Sample Test Paper-26

  • question_answer
    A body of mass m is kept on a rough horizontal surface of friction coefficient \[\mu \]. A force is applied horizontally, but the body is not moving. The net force F by the surface on the body will be:

    A)  \[F\le \mu mg\]

    B)  \[F=\mu mg\]

    C)  \[mg<F<mg\sqrt{1+{{\mu }^{2}}}\]

    D)  \[mg\ge F>mg\sqrt{1-{{\mu }^{2}}}\]

    Correct Answer: C

    Solution :

    If the body is not moving, \[F=f\] Where f is the force of friction of the body, clearly \[O\le F<\mu mg\] or  \[O\le F<\mu mg\,(=f)\] Now, the force by the surface on the body. \[F=\sqrt{{{f}^{2}}+{{R}^{2}}}\] \[=\sqrt{{{(\mu mg)}^{2}}+{{(mg)}^{2}}}\]              ??.(i) or        \[F=mg\,\sqrt{{{\mu }^{2}}+1}\]    ??.(ii) From equations (0 and (ii) we concludely \[\therefore \]  \[mg\le F\le mg\,\sqrt{1+{{\mu }^{2}}}\]


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