Question

The diameter of a brass wire is 0.6 mm and Y is $9\times {10}^{6}N{m}^{-2}.$The force which will increase its length by 0.2% is about

• A. 100 N
• B. 51 N
• C. 25 N
• D. none of these

Answer 1

The correct option is B 51 N

$F=\frac{YA△l}{l}$
$=9\times {10}^{10}\times \frac{22}{7}\times \frac{(0.6\times {10}^{-3}{)}^2}{4}\times \frac{0.2}{100}N$ =51 N approx