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NEET Sample Paper NEET Sample Test Paper-77

  • question_answer
    If one end of wire of length 4.5 m of radius 3 mm is fixed to a tree limb and a body weighing 100 N is tied to it then the elongation in the wire is \[\left( Y = 4.8 \times  1{{0}^{11}}N / {{m}^{2}} \right)\]

    A)  \[2.22\,\,\times \,\,1{{0}^{-\,5}}\,m\]    

    B)  \[3.22\,\,\times \,\,1{{0}^{-\,5}}\,m\]

    C)  \[5.5\,\,\times \,\,1{{0}^{-\,7}}\,m\]      

    D)  \[9.2\,\,\times \,\,1{{0}^{-\,12}}\,m\]

    Correct Answer: B

    Solution :

    \[Y=\frac{Stress}{Strain}=\frac{T/A}{l/L}\]where,            \[T = tension,\,\,\,A =Area,\] \[l\,\,=\,\,elongation\text{ }or\text{ }change\text{ }in\text{ }length,\] \[L =original length\] \[\Rightarrow \,\,\,\,\,\,\,\,l=\frac{TL}{AY}=\frac{100\times 4.5}{(3.14\times 9\times {{10}^{-\,6}})\times (4.8\times {{10}^{11}})}\] \[=\,\,\,\,3.22\,\,\times \,\,{{10}^{-\,5}}\,m\]


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