VMMC VMMC Medical Solved Paper-2013

  • question_answer
    Two planets are revolving around the earth with velocities \[{{\upsilon }_{1}}\]and \[{{\upsilon }_{2}}\]and in radii\[{{r}_{1}}\] and \[{{r}_{2}}({{r}_{1}}>{{r}_{2}})\] respectively. Then

    A) \[{{v}_{1}}={{v}_{2}}\]

    B)  \[{{v}_{1}}>{{v}_{2}}\]

    C)  \[{{v}_{1}}<{{v}_{2}}\]

    D)  \[\frac{{{v}_{1}}}{{{r}_{1}}}=\frac{{{v}_{2}}}{{{r}_{2}}}\]

    Correct Answer: B

    Solution :

     \[{{F}_{1}}=\frac{GMm}{r_{1}^{2}}=\frac{g{{R}^{2}}m}{r_{1}^{2}}\] \[GM=g{{R}^{2}}\] \[{{F}_{2}}=\frac{GMm}{r_{2}^{2}}=\frac{g{{R}^{2}}m}{r_{2}^{2}}\] \[\frac{g{{R}^{2}}m}{r_{1}^{2}}=\frac{mv_{1}^{2}}{{{r}_{1}}}\] \[v_{1}^{2}=\frac{g{{R}^{2}}}{{{r}_{1}}}\] \[\Rightarrow \] \[{{v}_{1}}=\sqrt{\frac{g{{R}^{2}}}{{{r}_{1}}}}\] \[{{v}_{2}}=\sqrt{\frac{g{{R}^{2}}}{{{r}_{2}}}}\frac{{{v}_{1}}}{{{v}_{2}}}\] \[=\sqrt{\frac{{{r}_{2}}}{{{r}_{1}}}}\] We can see that \[{{v}_{1}}>{{v}_{2}}\]


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