WB JEE Medical WB JEE Medical Solved Paper-2013

  • question_answer
    Infinite number of bodies, each of mass 2 kg are situated on \[x-\]axis at distance 1m, 2 m, 4 m, 8 m, respectively from the origin.  The resulting gravitational potential due to this system at the origin will be

    A)  \[-G\]

    B)  \[-\frac{8}{3}G\]

    C)  \[-\frac{4}{3}G\]

    D)  \[-4G\]

    Correct Answer: D

    Solution :

     The resulting gravitational potential, \[V=-2G\left[ \frac{1}{1}+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+... \right]\] \[\Rightarrow \] \[V=-2G\left[ 1+\frac{1}{2}+\frac{1}{{{2}^{2}}}+\frac{1}{{{2}^{3}}}... \right]\] \[\Rightarrow \] \[V=-2G{{\left( 1+\frac{1}{2} \right)}^{-1}}\] \[\Rightarrow \] \[V=-\frac{2G}{\left( 1-\frac{1}{2} \right)}=-\frac{2G}{\left( \frac{1}{2} \right)}=-4G\]


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