Question

The adjacent graph shows the extension $(\Delta l)$ of a wire of length $1 m$ suspended from the top of a roof at one end with a load $W$ connected to the other end. If the cross sectional area of the wire is $10^{-6} \,m^{2}$, calculate the young's modulus of the material of the wire

• A. $2 \times 10^{11} \,N / m ^{2}$
• B. $2 \times 10^{-11}\, N / m ^{2}$
• C. $3 \times 10^{-12}\, N / m ^{2}$
• D. $2 \times 10^{-13} \,N / m ^{2}$

Answer 1

Answer: (A)

From the graph $l=10^{-4} m, F=20 \,N$
$A=10^{-6} \,m^{2}, L=1 \,m$
$\therefore Y=\frac{F L}{A l}=\frac{20 \times 1}{10^{-6} \times 10^{-4}}$
$=20 \times 10^{10} $
$=2 \times 10^{11} \,N / m ^{2}$