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