MGIMS WARDHA MGIMS WARDHA Solved Paper-2003

  • question_answer
    A rocket is accelerated with speed \[\upsilon =2\sqrt{g{{R}_{e}}}\] near earth surface and then it moves upward. At far distance from the earth surface, the speed of the rocket will be:

    A) \[\sqrt{g{{R}_{e}}/2}\]                              

    B) \[\sqrt{g{{R}_{e}}}\]

    C) \[(2-\sqrt{2})\sqrt{g{{R}_{e}}}\]                               

    D) \[\sqrt{2g{{R}_{e}}}\]

    Correct Answer: C

    Solution :

     The escape velocity of rocket required to come out from earth is given by \[{{\upsilon }_{e{{s}_{1}}}}=\sqrt{2g{{R}_{e}}}\] The accelerated velocity near earth surface \[{{\upsilon }_{e{{s}_{2}}}}=2\sqrt{g{{R}_{e}}}\] \[\therefore \]At far distance, final velocity of rocket \[{{\upsilon }_{es}}={{\upsilon }_{e{{s}_{2}}}}-{{\upsilon }_{e{{s}_{1}}}}\]                 \[=2\sqrt{g{{R}_{e}}}-\sqrt{2g{{R}_{e}}}\]                 \[=\sqrt{g{{R}_{e}}}-(2-\sqrt{2})\]                 \[=(2-\sqrt{2})\sqrt{g{{R}_{e}}}\]


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