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JEE Main & Advanced JEE Main Paper (Held On 9 April 2017)

  • question_answer
    A steel rail of length 5 m and area of cross section \[40\,c{{m}^{2}}\] is prevented from expanding along its length while the temperature rises by\[{{10}^{\text{o}}}C\]. If coefficient of linear expansion and Young's modulus of steel are \[1.2\,\times {{10}^{-5}}\,{{K}^{-1}}\] and \[2\times {{10}^{11}}N{{m}^{-2}}\] respectively, the force developed in the rail is approximately: [JEE Online 09-04-2017]

    A)  \[2\times {{10}^{7}}N\]                               

    B)  \[2\times {{10}^{9}}N\]

    C)  \[3\times {{10}^{-5}}N\]                             

    D)  \[1\times {{10}^{5}}N\]

    Correct Answer: D

    Solution :

                      \[F=yA\propto \Delta t\] \[=2\times {{10}^{11}}\times 40\,\times {{10}^{-4}}\,\times 1.2\,\times {{10}^{-5}}\times 10\] \[=9.6\,\times {{10}^{4}}=1\times {{10}^{5}}N\]


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