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. $2 \times 10^{11} \, Nm^{-2}$
• B. $2 \times 10^{-11} \, Nm^{-2}$
• C. $3 \times 10^{-12} \, Nm^{-2}$
• D. $2 \times 10^{-13} \, Nm^{-2}$

Answer 1

Answer: (A)

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