EAMCET Medical EAMCET Medical Solved Paper-2004

  • question_answer
    At \[0{}^\circ C\], the densities of a cork and a liquid, in which the cork floats are \[{{S}_{1}}\] and \[{{S}_{2}}\] respectively. The coefficients of expansion of the material of the cork and the liquid are 100r and respectively. If the cork sinks when temperature of the liquid is t \[{}^\circ C\], then the \[\left( \frac{{{P}_{2}}}{{{P}_{1}}} \right)\] is:

    A) \[\frac{1+100\gamma t}{1+\gamma t}\]                               

    B) \[\frac{1+\gamma t}{1+100\,\gamma t}\]

    C)                  \[\frac{100+\gamma t}{1+\gamma t}\]                                

    D)                  \[\frac{1+\gamma t}{100+\gamma t}\]

    Correct Answer: A

    Solution :

    Let \[\rho {{}_{1}}\]is the density of liquid at\[t{{\,}^{o}}C\] and \[\gamma \] is  the coefficient of expansion. Then,  \[p{{}_{2}}={{\rho }_{1}}(1-\gamma t)\]                                   ?(i) Similarly, if \[\rho {{}_{2}}\]is the density of cork having coefficient of expansion \[100\gamma \] at \[t{{\,}^{o}}C\] Then \[\rho {{}_{2}}={{\rho }_{2}}(1-\gamma t)={{\rho }_{2}}(1-100\gamma \,t)\]                        ?(ii) the cork will sink k at \[t{{\,}^{o}}C\] if \[\rho {{}_{1}}=\rho {{}_{2}}\] or            \[\frac{\rho {{}_{1}}}{\rho {{}_{2}}}=1\]                                                 ?(iii) Now, putting the values from Eqs. (i) and (ii) in Eq. (iii), we obtain \[\frac{{{\rho }_{1}}(1-\gamma t)}{{{\rho }_{2}}(1-100\gamma t)}=1\] \[\frac{{{\rho }_{2}}}{{{\rho }_{1}}}=\frac{1-\gamma t}{1-100\gamma t}\] or            \[\frac{{{\rho }_{2}}}{{{\rho }_{1}}}=\frac{{{(1-100\gamma t)}^{-1}}}{{{(1-\gamma t)}^{-1}}}\] \[\frac{{{\rho }_{2}}}{{{\rho }_{1}}}=\frac{1+100\gamma t}{(1+\gamma t)}\]  (using Binomial theorem)


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