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Question: Answered & Verified by Expert
The Poisson's ratio of a material is 0.4 . If a force is applied to a wire of this material, there is a decrease of cross-sectional area by $2 \%$. The percentage increase in its length is
PhysicsMechanical Properties of SolidsTS EAMCETTS EAMCET 2002
Options:
  • A $3 \%$
  • B $2.5 \%$
  • C $1 \%$
  • D $0.5 \%$
Solution:
2408 Upvotes Verified Answer
The correct answer is: $2.5 \%$
$\begin{aligned} & \text { Poission's ratio } \sigma=\frac{\Delta R / R}{\Delta l / l} \\ & \frac{\Delta l}{l}=\frac{\Delta R}{R} \times \frac{1}{\sigma} \\ & =\frac{\Delta R}{R} \times \frac{1}{0.4} \\ & \therefore \text { Increase in length }=\left(\frac{\Delta R}{R} \times \frac{1}{0.4}\right) \times 100 \\ & =\frac{2}{2} \times \frac{1}{0.4}=2.5 \% \\ & \end{aligned}$

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