Question

The breaking stress for a substance is ${10}^{6}N/m^2$. What length of the wire of this substance should be suspended vertically so that the wire breaks under its own weight?
(Given : density of material of the wire $=4\times {10}^{3}kg/m^3$ and $g=10m/s^2)$.

• A. $10m$
• B. $15m$
• C. $25m$
• D. $34m$

Answer 1

The correct option is C $25m$

$Breakingstress=\frac{Maximumweight}{\text{Area of cross section}}$
${10}^6=\frac{al\rho g}{a}=l\rho g$
or $l=\frac{{10}^6}{\rho g}=\frac{{10}^6}{4\times {10}^3\times 10}m=25m$.