Question

A wire has a breaking stress $6\times {10}^{5}N/m^2$ and a density of $3\times {10}^{4}N/m^3$. The length of the wire of the same material which will break under its own weight, (if=10m/{ s }^{ 2 })$ is.

• A. 2000 m
• B. 2500 m
• C. 20 m
• D. 2 m

Answer 1

Answer: (D)

2 m

$\begin{array}{c}\frac{F}{A}=\text{Stress}\\ \text{given Breaking Stress =}6\times {10}^{5}N/m^2\\ \text{Density}=3\times {10}^{4}N/m^3\\ \frac{l}{l}\times \frac{mg}{A}=\text{Stress}\end{array}$

$\begin{array}{c}\frac{m}{v}\times L\times g=\text{Breaking stress}\\ (3\times {10}^4)\times L\times 10=6\times {10}^5\\ L=2m\end{array}$