Question

Sound waves travel from air to water. The velocity of the sound waves in air is $332m{s}^{-1}$ and wavelength is 2 m. If the wavelength of the sound waves in water is 850 cm, find its velocity in water.

• A. $1400m{s}^{-1}$
• B. $1300m{s}^{-1}$
• C. $1411m{s}^{-1}$
• D. $1511m{s}^{-1}$

Answer 1

The correct option is C $1411m{s}^{-1}$

Speed of Sound in Air is given by, $v=u\lambda$ , where $v$ is speed, $u$ is frequency and $\lambda$ is wavelength of sound.

Let, $v_w$ and ${\lambda }_w$ are the speed and wavelength in Water.

and we know that, $u\left(Frequency\right)$ remains constant in both of the medium's.

$⟹$ $v_w=u{\lambda }_w$

Now, Given;

In Air

$v=332m/s$ $\lambda =2m$ , from this we can find $u\left(Frequency\right)=v/\lambda \cong 332/2=166Hz$

Also,

In Water

$v_w=u{\lambda }_w\cong 166\ast 850/100\cong 166\ast 8.5=1411m/s$

Hence, option C is correct.