KVPY Sample Paper KVPY Stream-SX Model Paper-4

  • question_answer
    An asteroid of mass m is approaching earth initially at a distance of \[10{{R}_{e}}\] with speed \[{{v}_{i}}.\] It hits the earth with a speed \[{{v}_{f}}\](\[{{R}_{e}}\] and \[{{M}_{e}}\]are radius and mass of earth), then

    A) \[v_{f}^{2}=v_{i}^{2}+\frac{2Gm}{{{M}_{e}}R}\left( 1-\frac{1}{10} \right)\]

    B) \[v_{f}^{2}=v_{i}^{2}+\frac{2G{{M}_{e}}}{{{R}_{e}}}\left( 1+\frac{1}{10} \right)\]

    C) \[v_{f}^{2}=v_{i}^{2}+\frac{2G{{M}_{e}}}{{{R}_{e}}}\left( 1-\frac{1}{10} \right)\]

    D) \[v_{f}^{2}=v_{i}^{2}+\frac{2Gm}{{{R}_{e}}}\left( 1-\frac{1}{10} \right)\]

    Correct Answer: C

    Solution :

    [c] \[-\frac{G{{M}_{e}}m}{10{{R}_{e}}}+\frac{1}{2}mv_{i}^{2}\]\[=-\frac{G{{M}_{e}}m}{{{\operatorname{R}}_{e}}}+\frac{1}{2}mv_{f}^{2}\] \[\therefore v_{f}^{2}=v_{i}^{2}+\frac{2G{{M}_{e}}}{{{\operatorname{R}}_{e}}}\left( 1-\frac{1}{10} \right)\]


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