Question

The breaking stress of a wire of length l and radius r is $5kg-wt/m^2$. The wire of length 2l and radius of 2 r of the same material will have breaking stress in $-wt/m^2$

• A. 2.5
• B. 10
• C. 20
• D. 80

Answer 1

Answer: (B)

10

$\begin{array}{cc}\text{Breaking stress of a wire}L\text{and radius}r=5\frac{kg}{m^2}& \\ \text{Breaking stress}& =\frac{F}{A}F=\text{due to its own weight}\\ & =\frac{mg}{\pi r^2}\\ & =\frac{Pvg}{\pi r^2}\\ & =\frac{P\pi r^{2}bg}{\pi r^2}\end{array}$

Breaking stress $=$ Plg

Breaking stress $\alpha$ \&

So, For wire of length 2 l having same material (f)

have $=2\times 5kg/m^2$ $=10kg/m^2$