BCECE Medical BCECE Medical Solved Papers-2003

  • question_answer
    Pressure inside two soap bubbles are 1.01 and 1.02 atm. Ratio between their volumes is :

    A)  102 : 101     

    B)  \[{{(102)}^{3}}\text{:(}103{{)}^{3}}\]

    C)  8 : 1           

    D)  2 : 1

    Correct Answer: C

    Solution :

    Let \[{{r}_{1}}\] and \[{{r}_{2}}\] be the radii of two soap bubbles. Excess pressure inside first soap bubble \[\frac{4T}{{{r}_{1}}}=1.01-1=0.01\] atm Excess pressure inside second soap bubble \[\frac{4T}{{{r}_{2}}}=1.02-1=0.02\] atm Therefore, \[\frac{4T/{{r}_{1}}}{4T/{{r}_{2}}}=\frac{0.01}{0.02}=\frac{1}{2}\] \[\Rightarrow \] \[\frac{{{r}_{2}}}{{{r}_{1}}}=\frac{1}{2}\] The ratio of their volumes is given by \[\frac{{{V}_{1}}}{{{V}_{2}}}=\frac{\frac{4}{3}\pi {{r}_{1}}^{3}}{\frac{4}{3}\pi r_{2}^{3}}\] \[\Rightarrow \] \[\frac{{{V}_{1}}}{{{V}_{2}}}={{\left( \frac{{{r}_{1}}}{{{r}_{2}}} \right)}^{3}}\] \[={{\left( \frac{2}{1} \right)}^{3}}\]


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