AFMC AFMC Solved Paper-2004

  • question_answer
    Pressure gradient has the same dimensions as that of:

    A) velocity gradient             

    B) potential gradient

    C) energy gradient               

    D) none of these

    Correct Answer: C

    Solution :

    In order to arrive at the correct answer we solve for dimensional formula of each individually. Pressure gradient\[=-\frac{\Delta P}{\Delta x}=\frac{N/{{m}^{2}}}{m}\] \[\therefore \] Dimensions of \[\left( \frac{\Delta P}{\Delta x} \right)=\frac{[ML{{T}^{2}}]/[{{L}^{2}}]}{[L]}\]       \[=[M{{L}^{-2}}{{T}^{-2}}]\] Dimension of velocity gradient \[=\left[ -\frac{\Delta v}{\Delta x} \right]=\frac{m/s}{m}=\frac{[L{{T}^{-1}}]}{[L]}\] \[=[{{M}^{0}}{{L}^{0}}{{T}^{-1}}]\] Dimensions of potential gradient                \[=\left( -\frac{\Delta V}{\Delta x} \right)\frac{\Delta W/Q}{\Delta x}=\frac{[ML{{T}^{-2}}][L]}{[AT][L]}\] \[=[ML{{T}^{-3}}{{A}^{-1}}]\] Energy gradient\[=-\frac{\Delta E}{\Delta x}=\frac{Nm}{m}\] \[\therefore \]   Dimensions of \[\left( \frac{\Delta E}{\Delta x} \right)=\frac{[ML{{T}^{-2}}][L]}{[L]}\]                                 \[=[ML{{T}^{-2}}]\] As observed from above results we see that none of the dimensions are same as of pressure gradient hence, option (c) is correct.


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