Question

If Youngs modulus of the material of a rod is $2\times {10}^{11}N{m}^{-2}$ and density is 8000 kgm ${}^{-3}$ the time taken by a sound wave to travel through 2 m of the rod is :

• A. $1.11\times {10}^{-4}s$
• B. $3\times {10}^{-4}s$
• C. $4\times {10}^{-4}$
• D. $1\times {10}^{-4}s$

Answer 1

The correct option is C $4\times {10}^{-4}$

Velocity, $V=\sqrt{\frac{Y}{\rho }}=\sqrt{\frac{2\times {10}^{11}}{8000}}=\frac{{10}^4}{2}$

Distance is $2m$.

$\therefore$ Time taken $t=\frac{d}{v}=\frac{2}{\frac{{10}^4}{2}}s$$=4\times {10}^{-4}s$