A thunderclap sends a sound wave through the air and the ocean below. The thunderclap sound wave has a constant frequency of 20 Hz. What is the wavelength of the sound wave in water? (The equation for the speed of a wave is [tex]$v=f \times \lambda$[/tex].)

[tex]\[
\begin{tabular}{|c|c|c|c|c|}
\hline & Water & Diamond & Glass & Air \\
\hline
\begin{tabular}{c}
Speed of \\
sound \\
$(m/s)$
\end{tabular}
& 1,493 & 12,000 & 5,640 & 346 \\
\hline
\end{tabular}
\][/tex]

A. 64.5 m
B. 17.3 m
C. 74.7 m
D. 54.3 m



Answer :

To determine the wavelength of the sound wave in water, we use the wave equation:

[tex]\[ v = f \times \lambda \][/tex]

Here:
- [tex]\( v \)[/tex] is the speed of sound in the medium (in this case, water).
- [tex]\( f \)[/tex] is the frequency of the wave.
- [tex]\( \lambda \)[/tex] is the wavelength of the wave.

We need to find [tex]\(\lambda\)[/tex], so we rearrange the equation to solve for [tex]\(\lambda\)[/tex]:

[tex]\[ \lambda = \frac{v}{f} \][/tex]

Given:
- The speed of sound in water ([tex]\( v \)[/tex]) is 1,493 m/s.
- The frequency of the sound wave ([tex]\( f \)[/tex]) is 20 Hz.

Substituting these values into the equation:

[tex]\[ \lambda = \frac{1493 \, \text{m/s}}{20 \, \text{Hz}} \][/tex]

[tex]\[ \lambda = 74.65 \, \text{m} \][/tex]

Therefore, the wavelength of the sound wave in water is [tex]\( 74.65 \, \text{m} \)[/tex].

Given the options:
A. 64.5 m
B. 17.3 m
C. 74.7 m
D. 54.3 m

The closest match to our calculated wavelength is option C.

Thus, the correct answer is C. 74.7 m.