9th Class Science Gravitation and Floatation Question Bank Gravitation

  • question_answer
    The mass of the Jupiter is \[\text{1}\text{.9 }\times \text{ 1}0\text{27}\]kg and that of the sun is \[\text{1}\text{.99 }\times \text{ 1}0\text{38}\] kg. The mean distance of the Jupiter from the sun is \[\text{7}\text{.8 }\times \text{ 1}0\text{11}\] m. Speed of the Jupiter is (assuming that Jupiter moves in a circular orbit around the sun)

    A)   \[\text{1}\text{.3}0\text{4 }\times \text{ 1}{{0}^{\text{4}}}\text{m}/\text{sec}\]  

    B)  \[\text{13}.0\text{4 }\times \text{1}{{\text{0}}^{4}}\text{m}/\text{sec}\]

    C)  \[\text{1}\text{.3}0\text{4 }\times \text{1}{{\text{0}}^{\text{6}}}\text{m}/\text{sec}\]

    D) \[1.304\,\times {{10}^{2}}m/sec\]

    Correct Answer: A

    Solution :

     \[F=\frac{GMM}{{{r}^{2}}}\] \[=\frac{6.67\times {{10}^{-11}}\times (1.99\times {{10}^{30}})\times (1.9\times {{10}^{27}})}{{{(7.8\times {{10}^{11}})}^{2}}}\] \[=4.14\times {{10}^{23}}N\] Now let its speed of Jupiter be\[v\], then                 \[F=\frac{m{{v}^{2}}}{R}\] \[\Rightarrow \]               \[v=\sqrt{\frac{FR}{m}}\]                 \[=\sqrt{\frac{(7.8\times {{10}^{11}})\times (4.10\times {{10}^{23}})}{(1.9\times {{10}^{27}})}}\]                 \[=\mathbf{1}\mathbf{.34\times 1}{{\mathbf{0}}^{\mathbf{4}}}\mathbf{m/sec}\]


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