J & K CET Medical J & K - CET Medical Solved Paper-2013

  • question_answer
    The Youngs modulus of a rope of 10 m length and having diameter of 2 cm is\[200\times {{10}^{11}}\]dyne\[/c{{m}^{2}}\]. If the elongation produced in the rope is 1 cm, the force applied on the rope is

    A)  \[6.28\times {{10}^{5}}N\]      

    B)  \[6.28\times {{10}^{4}}N\]

    C)  \[6.28\times {{10}^{4}}\]dyne   

    D) \[6.28\times {{10}^{5}}\]dyne

    Correct Answer: B

    Solution :

     Youngs modulus of a rope\[Y=\frac{FL}{A\Delta l}\] Given, \[L=10\text{ }m,\text{ }A=\pi {{r}^{2}}=\pi {{(1)}^{2}}=\pi ;\] \[Y=20\times {{10}^{11}}dyne/c{{m}^{2}},\text{ }\Delta l=1cm,\] \[F=\frac{Y.A.\Delta l}{L}\] \[F=\frac{20\times {{10}^{11}}\times 1\times 1}{10\times {{10}^{2}}}\] \[F=6.28\times {{10}^{9}}dyne\] \[F=6.28\times {{10}^{4}}N\]


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