Manipal Engineering Manipal Engineering Solved Paper-2010

  • question_answer
    The time period of a geostationary satellite at a height 36000 km is 24 h. A spy satellite orbits earth at a height 6400 km. What will be the time period of spy satellite? [Radius of the earth = 6400 km]

    A)  5 h                                        

    B)  4 h

    C)  3h                         

    D)         12 h

    Correct Answer: B

    Solution :

    From Keplers third law of planetary motion                 \[{{T}^{2}}\propto {{R}^{3}}\] \[\therefore \]  \[\frac{T_{2}^{2}}{T_{1}^{2}}=\frac{R_{2}^{3}}{R_{1}^{3}}\] or            \[\frac{T_{2}^{2}}{{{(24)}^{2}}}={{\left( \frac{6400+6400}{36000+6400} \right)}^{2}}\] or            \[T_{2}^{2}={{(24)}^{2}}\times {{\left( \frac{16}{53} \right)}^{3}}\] \[\Rightarrow \]               \[{{T}_{2}}=4h\]


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