Question

a steel wire of mass 3.16 Kg is stretched to a tensile strain of $1\times {10}^{-3}$. The elastic deformation energy if density p=7.9 g/cc and $y=2\times {10}^{11}N/m^2$

• A. 4 KJ
• B. 0.4 KJ
• C. 0.04 KJ
• D. 4 J

Answer 1

The correct option is C 0.04 KJ

$\begin{array}{cc}E& =\frac{1}{2}\times \text{stress}\times \text{strain}\times v\\ & =\frac{1}{2}xy\times (8+8\sin {)}^2\times \frac{m}{c}\\ & =\frac{1}{2}{x}^2\times {10}^{\prime \prime }\times {10}^{-6}\times \frac{3.16}{7.9\times {10}^{23}}=\frac{316}{7.9}=405=0.04kJ\end{array}$