Railways Technical Ability Fluid Mechanics and Machinery Question Bank Fluid Mechanics

  • question_answer Which of the following is not a dimensionless group?

    A) \[\frac{\Delta \,p}{\rho \,{{N}^{2}}{{D}^{2}}}\]                     

    B) \[\frac{g\,H}{{{N}^{2}}\,{{D}^{2}}}\]

    C) \[\frac{\rho \,\omega \,{{D}^{2}}}{\mu }\]                    

    D) \[\frac{\Delta \,p}{\rho \,{{V}^{3}}}\]

    Correct Answer: D

    Solution :

    \[\frac{\Delta p}{p{{v}^{3}}}=\frac{m{{L}^{-1}}{{T}^{-2}}}{[M{{L}^{-3}}]\,[L{{T}^{-1}}]}={{M}^{1-1}}\,{{L}^{-1+3+3}}{{T}^{-2+3}}\]\[={{L}^{-1}}T,\] Which is non-dimensional


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