$A$ bob of mass $m$ is attached to a string whose other end is tied to a light vertical rod as shown in figure. The bob is swinging in horizontal plane with constant angular speed $\omega$. The vertical rod is supported on a block of mass $M$ which is placed on a rough surface. What is minimum friction coefficient between ground and block for which block does not slip ?

816-28

  • A

    $\frac{{m\,\cos \,\theta }}{{m\, + M}}$

  • B

    $\frac{{m\,\tan \,\theta }}{{m\, + M}}$

  • C

    $\frac{{3m\,\tan \,\theta }}{{m\, + M}}$

  • D

    $\frac{{M\,\tan \,\theta }}{{m\, + M}}$

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