Question

A 0.1 kg mass is suspended from a wire of negligible mass. The length of the wire is 1 m and its cross- sectional area is $4.9\times {10}^{-7}{m}^2$ If the mass is pulled a little in the vertically downward direction and released, it performs simple harmonic motion of angular frequency 140 rad $s^{-1}$ If the Young's modulus of the material of the wire is $n\times {10}^{9}N{m}^{-2}$, the value of n is

• A. 4
• B. 2
• C. 8
• D. 1

Answer 1

The correct option is A 4

$\omega =\sqrt{\frac{YA}{mL}}$
$140=\sqrt{\frac{n\times {10}^9\times 4.9\times {10}^{-7}}{0.1\times 1}}$
$n=4$