BCECE Engineering BCECE Engineering Solved Paper-2002

  • question_answer
    The dimensions of gravitational constant G are:

    A)  \[\text{ }\!\![\!\!\text{ M}{{\text{L}}^{\text{3}}}{{\text{T}}^{\text{-2}}}\text{ }\!\!]\!\!\text{ }\]                            

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

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

    D)         \[\text{ }\!\![\!\!\text{ }{{\text{M}}^{-1}}{{\text{L}}^{3}}{{\text{T}}^{\text{-2}}}\text{ }\!\!]\!\!\text{ }\]

    Correct Answer: D

    Solution :

    Key Idea: From definition, gravitational constant is equal in magnitude to that force of attraction which acts between two particles each of unit mass separated by a unit distance. Numerically, gravitational constant \[G=\frac{F{{r}^{2}}}{{{m}_{1}}{{m}_{2}}}\] where F is force, r is the distance between the two masses \[{{m}_{1}}\]and \[{{m}_{2}}.\] Writing the dimensions of all the quantities in the above formula, the dimensions of G are             \[[G]=\frac{[ML{{T}^{-2}}][{{L}^{2}}]}{[M][M]}=[{{M}^{-1}}{{L}^{3}}{{T}^{-2}}]\]


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