Question

The velocity of sound in air is $336\text{m/s}$ and in water it is $1440\text{m/s}$. Wavelength of sound waves in air is $1.75\text{m}$. What is the frequency and wavelength of sound waves in water? $\left[7\text{marks}\right]$

Answer 1

Given:
Velocity of sound in air, $v=336\text{m/s}$
Velocity of sound in water, $v=1440\text{m/s}$
Wavelength of sound waves in air, $\lambda =1.75\text{m}$
So the frequency of sound in air, $f=\frac{v}{\lambda }=\frac{336}{1.75}$
$⟹f=192\text{Hz}$
$\left[3\text{marks}\right]$
Frequency does dont change with the medium, it is the property of the source of sound. So, the frequency in water will remain the same that is $192\text{Hz}$. $\left[2\text{marks}\right]$
So the wavelength of wave in water will be, ${\lambda }_w=\frac{v}{f}$
$⟹{\lambda }_w=\frac{1440}{192}=7.5\text{m}$
$\left[2\text{marks}\right]$