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NEET Sample Paper NEET Sample Test Paper-73

  • question_answer
    Increase in length of a wire is 1 mm when suspended by a weight. If the same weight is suspended on a wire of double its length and double its radius, the increase in length will be

    A) 2 mm               

    B) 0.5 mm

    C) 4 mm               

    D) 0.25 mm

    Correct Answer: B

    Solution :

    \[l=\frac{FL}{AY}\,\,\,\Rightarrow \,\,\,l\propto \frac{L}{{{r}^{2}}}\]       (F and Y are same) \[\therefore \,\,\,\,\,\,\,\frac{{{l}_{2}}}{{{l}_{1}}}=\frac{{{L}_{2}}}{{{L}_{1}}}{{\left( \frac{{{r}_{1}}}{{{r}_{2}}} \right)}^{2}}=2\times {{\left( \frac{1}{2} \right)}^{2}}=\frac{1}{2}\] \[\Rightarrow \,\,\,\,\,\,\,{{l}_{2}}=\frac{{{l}_{1}}}{2}=\frac{l}{2}=0.5\,\,mm\]


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