Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2011

  • question_answer
    A metal bar of length L and area of cross-section A is clamped between two rigid supports. Its Young's modulus for the material of the rod is Y and coefficient of linear expansion is a. If the temperature of the rod is increased by \[\Delta t{}^\circ C\] the force exerted by the rod on the supports is

    A)  \[YAL\Delta t\]                                

    B) \[YA\alpha \Delta t\]

    C) \[\frac{YA\alpha \Delta t}{A}\]                  

    D) \[Y\alpha A\Delta t\]

    Correct Answer: B

    Solution :

    Young?s elasticity coefficient \[Y=\frac{Fl}{A\Delta l}\] According to definition of linear expansion coefficient                 \[\Delta l=\alpha l\Delta t\] where,       \[l=\] initial length                 \[Y=\frac{Fl}{A\,\alpha \,\,l\Delta t}\] or            \[Y=\frac{F}{A\alpha \Delta t}\]                 \[F=YA\alpha \Delta t\] where, F = force applied on wire A = area of cross-section of wire \[\Delta t\] = increase in temperature of wire.


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