CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    A 4 m long copper wire of cross-sectional area \[1.2c{{m}^{2}}\]is stretched by a force of\[4.8\times {{10}^{3}}N\]. Youngs modulus for copper\[(Y=1.2\times {{10}^{11}}N/{{m}^{2}})\]the increase in length of wire is:

    A)  1.32 mm       

    B)         0.8 mm

    C)  0.48 mm       

    D)         5.36 mm

    E)  2.45 mm

    Correct Answer: A

    Solution :

    \[Stress=\frac{Force}{Area}=\frac{4.8\times {{10}^{3}}}{1.2\times {{10}^{-4}}}=4\times {{10}^{7}}N/{{m}^{2}}\] Youngs modulus,\[Y=\frac{stress}{strain}\] \[\Rightarrow \] \[Strain=\frac{4\times {{10}^{7}}}{1.2\times {{10}^{-4}}}=3.3\times {{10}^{-4}}\] \[\therefore \]Increase in length = longitudinal strain\[\times \]initial length                 \[=(3.3\times {{10}^{-4}})\times 4\]                 \[=13.2\times {{10}^{-4}}m=1.32\,mm\]


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