NEET Sample Paper NEET Sample Test Paper-73

  • question_answer
    If a particle of mass m is moving in a horizontal circle of radius r with a centripetal force \[\left( -k/{{r}^{2}} \right)\]the total energy is

    A) \[-\frac{k}{2r}\]            

    B) \[-\frac{k}{r}\]

    C) \[-\frac{2\,k}{r}\]                       

    D) \[-\frac{4\,k}{r}\]

    Correct Answer: A

    Solution :

    \[\frac{m{{\nu }^{2}}}{r}=\frac{k}{{{r}^{2}}}\,\,\Rightarrow \,\,m{{\nu }^{2}}=\frac{k}{r}\,\,\,\,\therefore \,\,\,KE=\frac{1}{2}m{{\nu }^{2}}=\frac{k}{2r}\] \[PE=\int{Fdr}=\int{\frac{k}{{{r}^{2}}}dr=-\frac{k}{r}}\] \[\therefore \,\,\,\,Total\,\,energy\,\,=\,\,KE+PE=\frac{k}{2r}-\frac{k}{r}=-\frac{k}{2r}\]


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