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NEET Sample Paper NEET Sample Test Paper-71

  • question_answer
    Steel and copper wires of the same length are stretched by the same weight one after the other. Young?s modulus of steel and copper are\[2 \times  1{{0}^{11}}\,N/{{m}^{2}}\,and 1.2 \times  1{{0}^{11}}\,N/{{m}^{2}}\]. The ratio of increase in length

    A) \[\frac{2}{5}\]                          

    B) \[\frac{3}{5}\]

    C) \[\frac{5}{4}\]                          

    D) \[\frac{5}{2}\]

    Correct Answer: B

    Solution :

    \[l=\frac{FL}{AY}\,\,\,\,\,\,\,\,\Rightarrow \,\,\,\,\,\frac{{{l}_{S}}}{{{l}_{cu}}}=\frac{{{Y}_{cu}}}{{{Y}_{S}}}\,\,\,\,(F,\,\,L\,\,and\,\,Y\,\,are\,\,constant)\]\[\,\therefore \,\,\,\,\,\,\,\frac{{{l}_{s}}}{{{l}_{cu}}}=\frac{1.2\times {{10}^{11}}}{2\times {{10}^{11}}}=\frac{3}{5}\]


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