BCECE Engineering BCECE Engineering Solved Paper-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)  70 km                  

    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            \[T=\frac{2\pi \sqrt{{{R}_{e}}+h}}{\sqrt{9.32}}\] \[\therefore \]  \[5.26\times {{10}^{3}}=\frac{2\times 3.14\sqrt{{{R}_{e}}+h}}{3.05}\] \[\sqrt{{{R}_{e}}+h}=2.55\times {{10}^{3}}\] \[{{R}_{e}}+h=6.53\times {{10}^{6}}\] \[h=6.53\times {{10}^{-6}}-6.37\times {{10}^{6}}\] \[=0.16\times {{10}^{6}}\,m\] \[=160\times {{10}^{3}}\,m=160\,km\]


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