Question

The adjacent graph shows the extension $(\Delta l)$ of a wire of length $1 m$ suspended from the top of a root at one end with a load $W$ connected to the other end. If the crosssectional 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}} $
$=20 \times 10^{10}=2 \times 10^{11} N / m ^2$