NEET Sample Paper NEET Sample Test Paper-60

  • question_answer
    The velocity of water waves may depend upon their wavelength\[\lambda \], the density of water p and the acceleration due to gravity g. The method of dimensions gives the relation between these quantities as:

    A) \[{{v}^{2}}\propto \lambda {{g}^{-1}}{{\rho }^{-1}}\]                     

    B) \[{{v}^{2}}\propto \,g\lambda \rho \]

    C) \[{{v}^{2}}\propto \,g\lambda \]

    D) \[{{v}^{2}}\propto \,{{g}^{-1}}\lambda {{\rho }^{-3}}\]

    Correct Answer: C

    Solution :

    [c] \[v\,\propto \,{{(\lambda )}^{a}}\,{{(\ell )}^{b}}{{(g)}^{c}}\] \[v\,\propto \,{{(L)}^{a}}\,{{(M{{L}^{-3}})}^{b}}{{(L{{T}^{-2}})}^{c}}\] \[v=k\,{{M}^{b}}\,{{L}^{a-3b+c}}{{T}^{-2c}}\] \[L{{T}^{-1}}=k\,{{M}^{b}}{{L}^{a-\,3b+c}}\,{{T}^{-2c}}\] \[a-3b+c=1,-2c=-1b=0\] \[a-3\times 0+\frac{1}{2}=1,\,\,\,c=\frac{1}{2}\] \[a=\frac{1}{2}\] \[v=k\,{{(\lambda )}^{{}^{1}/{}_{2}}}{{(\ell )}^{o}}\,{{(g)}^{{}^{1}/{}_{2}}}\] \[{{V}_{2}}=k(\lambda )(g)\]                                                                                         


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