BCECE Engineering BCECE Engineering Solved Paper-2001

  • question_answer
    In the equation\[\left( P+\frac{a}{{{V}^{2}}} \right)(V-b)=RT,\] where P = pressure, V= volume, a and b are constants, the dimensions of a are:

    A)  \[\text{ }\!\![\!\!\text{ M}{{\text{L}}^{\text{5}}}{{\text{T}}^{\text{-1}}}\text{ }\!\!]\!\!\text{ }\]                            

    B)  \[\text{ }\!\![\!\!\text{ M}{{\text{L}}^{\text{-5}}}{{\text{T}}^{\text{-1}}}\text{ }\!\!]\!\!\text{ }\]           

    C)        \[\text{ }\!\![\!\!\text{ M}{{\text{L}}^{5}}{{\text{T}}^{\text{-2}}}\text{ }\!\!]\!\!\text{ }\]           

    D)         \[\text{ }\!\![\!\!\text{ }{{\text{M}}^{\text{-1}}}{{\text{L}}^{5}}{{\text{T}}^{\text{-2}}}\text{ }\!\!]\!\!\text{ }\]

    Correct Answer: C

    Solution :

    Key Idea: According to principle of homogeneity of dimensions, the dimensions of all the terms in a physical expression should be same. We have given \[\left( p+\frac{a}{{{V}^{2}}} \right)(V-b)=RT\] According to principle of homogeneity, \[[P]=\left[ \frac{a}{{{V}^{2}}} \right]\]                 or            \[[a]=[P][{{V}^{2}}]\]                 or            \[[a]=[M{{L}^{-1}}{{T}^{-2}}][{{L}^{6}}]\]                 \[\therefore \]  \[[a]=[M{{L}^{5}}{{T}^{-2}}]\] Note: The physical quantities separated by the symbols \[+,-,=,>,<\] etc., have the same dimensions.


You need to login to perform this action.
You will be redirected in 3 sec spinner