JEE Main & Advanced Sample Paper JEE Main - Mock Test - 27

  • 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 \[9.32\,m\,{{\text{s}}^{-2}}\]. The height of the satellite orbit above the earths surface is (Radius of earth \[=6.37\times {{10}^{6}}m\])

    A) 70 km    

    B) 160 km

    C) 190 km             

    D) 220 km

    Correct Answer: B

    Solution :

    [b]: Time period of revolution of satellite \[T=2\pi \sqrt{\frac{{{({{R}_{e}}+h)}^{3}}}{G{{M}_{e}}}}\]or\[\frac{{{T}^{2}}}{4{{\pi }^{2}}}=\frac{{{({{R}_{e}}+h)}^{3}}}{G{{M}_{e}}}\]        ?(i) Centripetal acceleration, \[a=\frac{G{{M}_{e}}}{{{({{R}_{e}}+h)}^{2}}}\]or\[\frac{{{({{R}_{e}}+h)}^{2}}}{G{{M}_{e}}}=\frac{1}{a}\]                                                ?.(ii) Divide (i) by (ii), we get \[({{R}_{e}}+h)=\frac{{{T}^{2}}}{4{{\pi }^{2}}}\times a={{\left( \frac{5.26\times {{10}^{3}}}{2\pi } \right)}^{2}}\times 9.32\] \[{{R}_{e}}+h=6.53\times {{10}^{6}}m\] \[h=6.53\times {{10}^{6}}m-6.37\times {{10}^{6}}m=0.16\times {{10}^{6}}m\] \[=160\times {{10}^{3}}m=160km\]


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