NEET Physics Mathematical Tools, Units & Dimensions NEET PYQ-Mathematical Tools, Units and Dimensions

  • question_answer
    The density of material in CGS system of units is \[4g/c{{m}^{3}}\]. In a system of units in which unit of lengths is 10 cm and unit of mass' is 100 g, the value of density of material will be' [AIPMT (M) 2011]

    A) 0.4

    B) 40  

    C) 400

    D) 0.04                         

    Correct Answer: B

    Solution :

    Mass,    \[M=dV\]
    \[d=\frac{M}{{{L}^{3}}}\]
    \[d=4\,g/c{{m}^{3}}\]
    If unit of mass is 100 g and unit of distance is
    10 cm.
    So, density \[=\frac{4\left( \frac{100g}{100} \right)}{{{\left( \frac{10}{10}cm \right)}^{3}}}\]
                \[=\frac{\left( \frac{4}{100} \right)}{{{\left( \frac{1}{10} \right)}^{3}}}.\frac{(100\,g)}{{{(10\,cm)}^{3}}}\]
                \[=40\,g\,c{{m}^{-3}}\]
    Aliter     \[{{u}_{2}}={{u}_{1}}\left( \frac{{{M}_{1}}}{{{M}_{2}}} \right){{\left( \frac{{{L}_{1}}}{{{L}_{2}}} \right)}^{-3}}\]
                \[=4\left( \frac{1}{100} \right){{\left( \frac{1}{10} \right)}^{-3}}\]
                            \[=40\]
               


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