BCECE Medical BCECE Medical Solved Papers-2011

  • question_answer
    A satellite is moving in a circular orbit at a certain height above the earths surface. It takes \[5.26\times {{10}^{3}}s\] to complete one revolution with a centripetal acceleration equal to 9.32\[m/{{s}^{2}}\]. The height of satellite orbiting above the earth is (Earths radius \[=6.37\times {{10}^{6}}m\])

    A)  220 km

    B)  160 km

    C)  70km

    D)  120 km

    Correct Answer: B

    Solution :

    Given, \[T=5.26\times {{10}^{3}}\,s,\,a=9.32\,m/{{s}^{2}}\] Centripetal acceleration \[a=\frac{{{v}^{2}}}{r}=9.32\] or            \[{{v}^{2}}=9.32\,r\] or            \[v=\sqrt{9.32\,({{R}_{e}}+h)}\]                 \[T=\frac{2\pi \,({{R}_{e}}+h)}{v}=\frac{2\pi \,({{R}_{e}}+h)}{\sqrt{9..32\,({{R}_{e}}+h)}}\] or            \[T=\frac{2\pi \,\,\sqrt{{{R}_{e}}+h}}{\sqrt{9.32}}\] \[\therefore \] \[4.26\times {{10}^{3}}=\frac{2\times 3.14\,\,\sqrt{{{R}_{e}}+h}}{3.05}\]                 \[\sqrt{{{R}_{e}}+h}=2.55\times {{10}^{3}}\]                 \[{{R}_{e}}+h=6.53\times {{10}^{6}}\]                 \[h=6.53\times {{10}^{6}}-6.37\times {{10}^{6}}\]                 \[=0.16\times {{10}^{6}}m\] \[=160\times {{10}^{3}}m=160\,km\]


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