CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    The sun revolves around galaxy with speed of 250 km/s around the centre of Milky Way and its radius is\[3\times {{10}^{4}}\]light year. The mass of milky way in (kg) is:

    A)  \[6\times {{10}^{41}}\]                

    B)         \[5\times {{10}^{41}}\]

    C)  \[4\times {{10}^{41}}\]                                

    D)  \[3\times {{10}^{41}}\]

    E)  \[2\times {{10}^{41}}\]

    Correct Answer: D

    Solution :

    Mass of galaxy is given by \[M=\frac{{{v}^{2}}r}{G}\] Given, \[v=250\text{ }km/s=250\times {{10}^{3}}m/s\] \[r=3\times {{10}^{4}}\]light year\[=3\times {{10}^{4}}\times {{10}^{16}}\]                 \[\approx 3\times {{10}^{20}}m.\] \[\therefore \]  \[M=\frac{(250\times {{10}^{3}})\times 3\times {{10}^{20}}}{6.6\times {{10}^{-11}}}=3\times {{10}^{41}}kg\]


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