Question

In determination of young modulus of elasticity of wire, a force is applied and extension is recorded. Initial length of wire is $1m$ . The curve between extension and stress is depicted then young modulus of wire will be:

Answer 1

$Stress=\frac{F}{A}$

$=\frac{mg}{\pi r^2}$

diffrence in stress = $8000KN/m^2-4000KN/m^2$

$=4000KN/m^2$

diffrence in strain = $\frac{I}{L}$

$I=4mm-2mm=2mm$

$L=1mm$

$\frac{I}{L}=\frac{1}{1000|}$

youngs modulus = $\frac{Stress}{Strain}$

$=\frac{4000}{\frac{1}{1000}}$

$=4\times {10}^6$