AFMC AFMC Solved Paper-2007

  • question_answer
    A capillary tube is attached horizontally to a constant head arrangement. If the radius of the capillary tube is increased by 10%, then the rate of flow of liquid will change nearly by

    A) +10 %                                   

    B) +46 %

    C) -10 %                                    

    D) -40 %

    Correct Answer: B

    Solution :

    Volume o liquid flowing through capillary per second is given by \[V=\frac{\pi p{{r}^{4}}}{8\eta l}\] \[\therefore \]    \[V\propto {{r}^{4}}\] \[\Rightarrow \]   \[\frac{{{V}_{2}}}{{{V}_{1}}}={{\left( \frac{{{r}_{2}}}{{{r}_{1}}} \right)}^{4}}\] \[\therefore \]    \[{{V}_{2}}={{V}_{1}}{{\left( \frac{110}{100} \right)}^{4}}={{V}_{1}}{{(1.1)}^{4}}\] \[=1.4641\,V\] \[\therefore \]   \[\frac{\Delta V}{V}=\frac{{{V}_{2}}-{{V}_{1}}}{V}\] \[=\frac{1.4641\,V-V}{V}\] \[=0.46\] or \[46%\]


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