Question

A $100\, m$ long wire having cross-sectional area $6.25 \times 10^{-4} \, m ^2$ and Young's modulus is $10^{10} Nm ^{-2}$ is subjected to a load of $250 \, N$, then the elongation in the wire will be:

• A. $6.25 \times 10^{-3} m$
• B. $4 \times 10^{-3} m$
• C. $4 \times 10^{-4} m$
• D. $6.25 \times 10^{-6} m$

Answer 1

Answer: (B)

Elongation in wire $\delta=\frac{ F \ell}{ AY }$
$ \delta=\frac{250 \times 100}{6.25 \times 10^{-4} \times 10^{10}} $
$ \delta=4 \times 10^{-3} m$