NEET Physics Mathematical Tools, Units & Dimensions Question Bank Dimensions

  • question_answer
    If the time period \[(T)\]  of vibration of a liquid drop depends on surface tension \[(S)\], radius \[(r)\]  of the drop and density \[(\rho )\] of the liquid, then the expression of \[T\] is                    [AMU (Med.) 2000]

    A)             \[T=k\sqrt{\rho {{r}^{3}}/S}\]

    B)             \[T=k\sqrt{{{\rho }^{1/2}}{{r}^{3}}/S}\]

    C)             \[T=k\sqrt{\rho {{r}^{3}}/{{S}^{1/2}}}\]          

    D)             None of these

    Correct Answer: A

    Solution :

                    Let \[T\propto {{S}^{x}}{{r}^{y}}{{\rho }^{z}}\] by substituting the dimension of \[[T]=[T]\] \[[S]=[M{{T}^{-2}}],\,[r]=[L],\,[\rho ]=[M{{L}^{-3}}]\] and by comparing the power of both the sides \[x=-1/2,\,y=3/2,\,z=1/2\]                         so \[T\propto \sqrt{\rho {{r}^{3}}/S}\Rightarrow T=k\sqrt{\frac{\rho {{r}^{3}}}{S}}\]           


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