A copper wire was subjected to a tensile stress of 7.7 x 10\(^7\). Calculate the strain of the wire.
[Young modules = 1.1 x 10\(^11\) Nm\(^{-2}\)]
A
2. 0 x 10-5
B
7.0 x 10-3
C
7.0 x 10-4
D
2.2 x 10-4
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Young modules = \( \frac{\text{Tensile stress}}{\text{Tensile strain}}\)
= \( 1.1 \times 10^11 = \frac{7.7 \times 10^7}{\text{Tensile Strain}} \)
∴ Tensile strain = \( \frac{7.7 \times 10^7}{1.1 \times 10^{11}} \)
= \( 7.0 \times 10^{7-11}
= 7.0 \times 10^{-4} \)
Source: Myschool Past Questions Archive (Record #14379)