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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 43

  • question_answer
    A stress of \[3.18\times {{10}^{8}}N{{m}^{-2}}\] is appleid to a steel rod of length 1 m along its length. Its Young's modulus is \[2\times {{10}^{11}}N{{m}^{-2}}\]. Then the elongation produced in the rod in mm is

    A) \[3.18\]

    B)                    \[6.36\]

    C) \[5.18\]

    D)        \[1.59\]

    Correct Answer: D

    Solution :

    \[Y=\frac{\frac{F}{A}}{\frac{\Delta l}{l}}\] Given, \[\frac{F}{A}=\] stress \[=3.18\times {{10}^{8}}N{{m}^{-2}}\] \[1=1m,\]\[Y=2\times {{10}^{11}}N{{m}^{-2}}\] \[\Delta 1=\frac{A}{Y}=\frac{1\times 3.18\times {{10}^{8}}}{2\times {{10}^{11}}}=1.59\times {{10}^{-3}}m=1.59mm\]


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