Manipal Engineering Manipal Engineering Solved Paper-2012

  • question_answer
    If an edge of a cube measure 2 m with a possible error of 0.5 cm. Find the corresponding error in the calculated volume of the cube

    A) \[0.6\,\,{{m}^{3}}\]                        

    B) \[0.06\,\,{{m}^{3}}\]

    C) \[0.006\,\,{{m}^{3}}\]   

    D)        \[0.0006\,\,{{m}^{3}}\]

    Correct Answer: B

    Solution :

    Let\[x\]be the length of an edge of a cube and\[V\]be the volume of that cube. \[\therefore \]  \[V={{x}^{3}}\] On differentiating w.r.t.\[x\], we get                 \[\frac{dV}{dx}=3{{x}^{2}}\] Let\[5V\]be error in\[V\]and corresponding error\[\delta x\]in\[x\]. \[\therefore \]     \[\delta V=\frac{dV}{dx}\delta x=3{{x}^{2}}\delta x\] Given that,\[x=2\,\,\text{m}\]and\[\delta x=0.5\,\,cm=\frac{0.5}{100}m\] \[\therefore \]     \[\delta V=3{{(2)}^{2}}\left( \frac{0.5}{100} \right)\]                           \[=\frac{12\times 0.5}{100}=\frac{6}{100}=0.06\,\,{{m}^{3}}\]


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