CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

  • question_answer
    Two planets have radii\[{{r}_{1}}\]and\[{{r}_{2}}\]and densities \[{{d}_{1}}\]and\[{{d}_{2}}\]respectively. Then the ratio of acceleration due to gravity on them will be:

    A)  \[{{r}_{1}}{{d}_{1}}:{{r}_{2}}{{d}_{2}}\] 

    B)         \[{{r}_{1}}{{d}_{2}}:{{r}_{2}}{{d}_{1}}\]

    C)  \[r_{1}^{2}{{d}_{1}}:r_{2}^{2}{{d}_{2}}\]             

    D)         \[{{r}_{1}}:{{r}_{2}}\]

    E)  \[{{r}_{1}}/\sqrt{{{d}_{1}}}:{{r}_{2}}\sqrt{{{d}_{2}}}\]

    Correct Answer: A

    Solution :

    The relation between density (D) and acceleration due to gravity (g) is \[d=\frac{3g}{4\pi {{R}_{e}}G}\] \[\therefore \]  \[\frac{{{d}_{1}}}{{{d}_{2}}}=\frac{{{g}_{1}}}{{{r}_{1}}}\times \frac{{{r}_{2}}}{{{g}_{2}}}\] \[\Rightarrow \]               \[\frac{{{g}_{1}}}{{{g}_{2}}}=\frac{{{d}_{1}}{{r}_{1}}}{{{d}_{2}}{{r}_{2}}}\]


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