CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2009

  • question_answer
    The ratio of radii of earth to another planet is\[\frac{2}{3}\]and the ratio of their mean densities is\[\frac{4}{5}\]. If an astronaut can jump to1 a maximum height of 1.5m on the earth, with the same effort, the maximum height he can jump on the planet is

    A)  1 m                       

    B)         0.8 m

    C)  0.5m                    

    D)         1.25m

    E)  2m

    Correct Answer: C

    Solution :

    Given:     \[\frac{{{R}_{e}}}{{{R}_{p}}}=\frac{2}{3}\] \[\frac{{{d}_{e}}}{{{d}_{p}}}=\frac{4}{5}\] As         \[MG={{g}_{e}}R_{e}^{2}\] and        \[M={{d}_{e}}\times \frac{4}{3}\pi R_{e}^{2}\] \[\therefore \]  \[{{d}_{e}}\times \frac{4}{3}\pi R_{e}^{3}\times G={{g}_{e}}R_{e}^{2}\] Or           \[{{d}_{e}}\times \frac{4}{3}\pi {{R}_{e}}\times G={{g}_{e}}\]              ...(i) Similarly for planet \[{{d}_{p}}\times \frac{4}{3}\pi {{R}_{p}}G={{g}_{p}}\]            ...(ii) Dividing Eq. (i) by Eq. (ii) we get                 \[\frac{{{g}_{e}}}{{{g}_{p}}}=\frac{{{R}_{e}}}{{{R}_{p}}}\times \frac{{{d}_{e}}}{{{d}_{p}}}\]                 \[\frac{{{g}_{e}}}{{{g}_{p}}}=\frac{2}{3}\times \frac{4}{5}=\frac{8}{15}\] \[=0.5m\]


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