JEE Main & Advanced Sample Paper JEE Main Sample Paper-27

  • question_answer
    A solid uniform sphere resting on a rough horizontal plane is given a horizontal impulse directed through its centre sot that it starts sliding with an initial velocity \[{{v}_{0}}\]. When it finally starts rolling without slipping the speed of its centre is :

    A)  \[\frac{2}{7}{{v}_{0}}\]                                  

    B)  \[\frac{3}{7}{{v}_{0}}\]

    C)  \[\frac{5}{7}{{v}_{0}}\]                                  

    D)  \[\frac{6}{7}{{v}_{0}}\]

    Correct Answer: C

    Solution :

    Angular momentum will remain conserved along point of contact, \[I\omega =\] constant \[m{{v}_{0}}r\,=mvr+\frac{2}{5}\,m{{r}^{2}}\times \omega \,\,(\therefore \,\,\omega =\,\frac{v}{r})\] \[m{{v}_{0}}r\,=mvr+\frac{2}{5}m{{r}^{2}}\times \frac{v}{r}\Rightarrow \,{{v}_{0}}=v+\frac{2}{5}v\] \[{{v}_{0}}=\frac{7}{5}v\,\Rightarrow \,v=\frac{5}{7}\,{{v}_{0}}\]


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