Question

A wire is made of a material of density $10gc{m}^3$ and breaking stress $5\times {10}^{9}N/m^2$. What length of a wire will break under its own weight when suspended vertically

• A. $2\times {10}^{4}m$
• B. $3\times {10}^{4}m$
• C. $4\times {10}^{4}m$
• D. $5\times {10}^{4}m$

Answer 1

The correct option is D $5\times {10}^{4}m$

$5\times {10}^9=Stress$

$\Rightarrow 5\times {10}^9=\frac{mg}{A}$

$=P\frac{A}{A}lg$

$\Rightarrow 5\times {10}^9=\frac{10000}{m^3}\times l\times 10m/s^2$

$\Rightarrow l=5\times {10}^{4}m$