Question

Two similar wires under the same load yield elongation of $0.1mm$ and $0.05mm$ respectively. If the area of cross-section of the first wire is $4m{m}^2$, then the area of cross section of the second wire is

• A. $6m{m}^2$
• B. $8m{m}^2$
• C. $10m{m}^2$
• D. $12m{m}^2$

Answer 1

Answer: (B)

$8m{m}^2$

$l=\frac{FL}{AY}$
$\frac{A_1}{A_2}=\frac{l_1}{l_2}⟹A_2=A_1(\frac{0.1}{0.05})=2A_1=2\times 4=8m{m}^2$