Question

A copper wire of 3 mm diameter is bent into a circle and held with its end just in contact . If the maximum permissible strain in copper is 0.0025, what is the shortest length of the wire that can be used ............(in mm)

• A. 3769.911

Answer 1

The correct option is A 3769.911

Let the radius of the circle be R

Let f be the maximum stress in the wire
$\frac{f}{\left(\frac{d}{2}\right)}=\frac{E}{R}$

$\therefore \frac{d}{2R}=\frac{f}{E}=0.0025$

$\frac{3}{2R}=0.0025$

$\therefore R=600mm$

$\therefore Shortestlengthofthewire=2\pi R=2\pi \times 600=3769.9mm$