CMC Medical CMC-Medical VELLORE Solved Paper-2015

  • question_answer
    A block of mass m is placed on a surface with a vertical cross-section given by\[y=\frac{{{x}^{3}}}{6}.\] If the frictional coefficient is 0.5, the maximum height above the ground at which the block can be placed without slopping is

    A)  \[\frac{1}{6}\]                                  

    B)  \[\frac{1}{3}\]

    C)  \[\frac{1}{2}\]                                  

    D)  \[1\]

    E)  \[\frac{1}{10}\]

    Correct Answer: A

    Solution :

                    As mass\[m\]placed oy surface with vertical X-sectfon for which \[y=\frac{{{x}^{3}}}{6}\] Thus, \[\tan \theta =\frac{dy}{dx}=\frac{d\left( \frac{{{x}^{3}}}{6} \right)}{dx}=\frac{{{x}^{2}}}{2}\] At the condition of limiting equilibrium\[\mu =\tan \theta \] \[\Rightarrow \]               \[0.5=\frac{{{x}^{2}}}{2}\Rightarrow x=\pm \,1\] Now when \[x=1\] then, \[y=\frac{{{(1)}^{3}}}{6}=\frac{1}{6}\] and when \[x=-1\] then, \[y=\frac{{{(-1)}^{3}}}{6}=\frac{-1}{6}\]


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