Question

The elastic limit of brass is $379MPa$. What should be the Minimum diameter of a brass rod if it is to support a $400N$ load without exceeding its elastic limit ?

• A. $1.16mm$
• B. $0.90mm$
• C. $1.36mm$
• D. $1.00mm$

Answer 1

The correct option is A $1.16mm$

$\frac{F}{A}$ = stress
$\frac{400\times 4}{\pi d^2}=379\times {10}^6$
$d^2=\frac{1600}{\pi \times 379\times {10}^6}=1.34\times {10}^{-6}$
$d=\sqrt{1.34}\times {10}^{-3}=1.15\times {10}^{-3}m$