WB JEE Medical WB JEE Medical Solved Paper-2006

  • question_answer
    The potential energy of a particle varies with distance x from a fixed origin as \[V=\left( \frac{A\sqrt{x}}{x+B} \right);\] where A and B are constants. The dimensions of A B are:

    A)  \[[M{{L}^{5/2}}{{T}^{-2}}]\]                       

    B)  \[[M{{L}^{2}}{{T}^{-2}}]\]

    C)  \[[{{M}^{3/2}}{{L}^{3/2}}{{T}^{-2}}]\]   

    D)  \[[M{{L}^{7/2}}{{T}^{-2}}]\]

    Correct Answer: D

    Solution :

                     Given,        \[v=\frac{A\sqrt{x}}{x+B}\]                                   ?(i) Dimensions of v= dimensions of potentialenergy \[=[M{{L}^{2}}{{T}^{-2}}]\] From Eq. (i), Dimensions ofB= dimensions of\[x=[{{M}^{0}}L{{T}^{o}}]\] \[\therefore \]Dimensions of A \[=\frac{\text{dimensions}\,\text{of}\,v\times \text{dimensitons}\,\text{of}\,(x+B)}{\text{dimensions}\,\text{of}\,\sqrt{x}}\]                 \[=\frac{[M{{L}^{2}}{{T}^{-2}}][{{M}^{0}}L{{T}^{0}}]}{[{{M}^{0}}{{L}^{1/2}}{{T}^{0}}]}\]                 \[=[M{{L}^{5/2}}{{T}^{-2}}]\] Hence, dimensions ofAB \[=[M{{L}^{5/2}}{{T}^{-2}}][{{M}^{0}}L{{T}^{0}}]\] \[=[M{{L}^{7/2}}{{T}^{-2}}]\]


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