RAJASTHAN ­ PET Rajasthan PET Solved Paper-2012

  • question_answer
    Let two satellites X and Y revolves around a planet P in circular orbits of radii 4R and R respectively. If the speed of the satellite X is 3v, then the speed of satellite Y will be

    A)  \[6v\]

    B)  \[\frac{3v}{4}\]

    C)  \[12v\]           

    D)  \[\frac{3v}{2}\]

    Correct Answer: A

    Solution :

     The velocity v of a satellite varies inversely as the square root of the orbital radius r i.e., \[v\propto \frac{1}{\sqrt{r}}\] So,            \[\frac{{{v}_{x}}}{{{v}_{y}}}=\sqrt{\frac{{{r}_{B}}}{{{r}_{A}}}}\] Given,       \[{{v}_{x}}=3v\] and           \[\frac{{{r}_{B}}}{{{r}_{A}}}=\frac{R}{4R}=\frac{1}{4}\] \[\Rightarrow \] \[\frac{3v}{{{v}_{y}}}=\sqrt{\frac{1}{4}}=\frac{1}{2}\] Or \[{{v}_{y}}=2\times 3v=6v\]


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