Haryana PMT Haryana PMT Solved Paper-2002

  • question_answer
    The escape velocity from a spherical planet is     \[{{u}_{es.}}\]What is the escape velocity            corresponding to another planet of twice the        radius and half the mean density ?

    A)  \[\sqrt{2}{{u}_{es.}}\]                  

    B)  \[\frac{{{u}_{es}}}{\sqrt{2}}\]

    C)  \[2{{u}_{es}}\]                                

    D)  \[{{4}_{ue}}\]

    Correct Answer: A

    Solution :

                    Escape velocity \[{{\upsilon }_{es}}k=\sqrt{\frac{2GM}{R}}\] \[=\sqrt{\frac{2G\frac{4}{3}\pi {{R}^{3}}d}{R}}=R\sqrt{\frac{8}{3}\pi Gd}\] \[\frac{{{\upsilon }_{e{{s}_{1}}}}}{{{\upsilon }_{e{{s}_{2}}}}}=\frac{{{R}_{1}}}{{{R}_{2}}}\sqrt{\frac{{{d}_{1}}}{{{d}_{2}}}}\] \[\frac{{{\upsilon }_{es}}}{{{\upsilon }_{e{{s}_{2}}}}}=\frac{{{R}_{1}}}{2{{R}_{1}}}\sqrt{\frac{d}{d/2}}\] \[=\frac{1}{\sqrt{2}}\]                 \[\Rightarrow \]               \[{{\upsilon }_{e{{s}_{2}}}}=\sqrt{2}{{\upsilon }_{es}}\]


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