Question

The lengths of two wires of the same material and diameter are $100cm$ and $125cm$. If same force is applied on them, the elongation in the first wire is $4mm$. The elongation in the second wire (in mm) is

• A. $4$
• B. $5$
• C. $0.8$
• D. $1.25$

Answer 1

Answer: (B)

$5$

$L_1=100cm,L_2=125cm$
$\Delta L_1=4cm,\Delta L_2=?$
$A_1=A_2{Y}_1=Y_2,F_1=F_2$
$\frac{\Delta L_1}{L_1}=\frac{\Delta L_2}{L_2}$
$\frac{1250\times 4}{1000}=\Delta L_2$
$=5mm$