Haryana PMT Haryana PMT Solved Paper-2010

  • question_answer
    From the dimensional consideration which of the following equations is correct?

    A) \[T=2\pi \sqrt{\frac{{{R}^{3}}}{GM}}\]                   

    B)  \[T=2\pi \sqrt{\frac{GM}{{{R}^{3}}}}\]

    C)  \[T=2\pi \sqrt{\frac{GM}{{{R}^{2}}}}\]                  

    D)  \[T=2\pi \sqrt{\frac{{{R}^{2}}}{GM}}\]

    Correct Answer: A

    Solution :

                    Taking  \[T=2\pi \sqrt{\frac{{{R}^{3}}}{GM}}\] Substituting the dimensions, LHS        \[T=[T]\] RHS        \[2\pi \sqrt{\frac{{{R}^{3}}}{GM}}=\sqrt{\frac{[{{L}^{3}}]}{[{{M}^{-1}}{{L}^{3}}{{T}^{-2}}][M]}}\]                 \[=\sqrt{[{{T}^{2}}]}=[T]\] We get,  LHS=RHS Hence, the equation \[T=2\pi \sqrt{\frac{{{R}^{3}}}{GM}}\] is correct.


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