JEE Main & Advanced Physics Gravitation / गुरुत्वाकर्षण Question Bank Self Evaluation Test - Gravitation

  • question_answer
    Two rings each of radius 'a' are coaxial and the distance between their centres is a. The masses of the rings are\[{{M}_{1}}\text{ }and\text{ }{{M}_{2}}\]. The work done in transporting a particle of a small mass m from centre \[{{\operatorname{C}}_{1}} to {{C}_{2}}\]is :

    A) \[\frac{Gm\left( {{M}_{2}}-{{M}_{1}} \right)}{a}\]

    B)        \[\frac{Gm\left( {{M}_{2}}-{{M}_{1}} \right)}{a\sqrt{2}}\left( \sqrt{2}+1 \right)\]

    C) \[\frac{Gm\left( {{M}_{2}}-{{M}_{1}} \right)}{a\sqrt{2}}\left( \sqrt{2}-1 \right)\]

    D) \[\frac{Gm\left( {{M}_{2}}-{{M}_{1}} \right)}{\sqrt{2}}a\]

    Correct Answer: C

    Solution :

    [c] \[W=m\left( {{V}_{2}}-{{V}_{1}} \right)\] when,                \[{{V}_{1}}=-\left[ \frac{G{{M}_{1}}}{a}+\frac{G{{M}_{2}}}{\sqrt{2}a} \right],\] \[{{V}_{2}}=-\left[ \frac{G{{M}_{2}}}{a}+\frac{G{{M}_{1}}}{\sqrt{2}a} \right]\] \[\therefore \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,W=\frac{Gm\left( {{M}_{2}}-{{M}_{1}} \right)}{a\sqrt{2}}(\sqrt{2}-1)\]


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