Question

A sound wave is propagating as shown below. What is the speed of sound wave?

• A. $1/3cm/sec$
• B. $1cm/sec$
• C. $0.5cm/sec$
• D. $2cm/sec$

Answer 1

The correct option is C $0.5cm/sec$

We know that the speed of sound is given by the formula:

$v=\lambda f$

Where $\lambda$ is wavelength of the sound wave which is $=0.002cm$

And $f$ is frequency of sound wave which can be written as , $1/\text{(Time period)}$

The time taken by $3$ half cycle is given in the figure as $0.006sec$.

So the time taken by $1$ half cycle is $=0.006/3=0.002sec$

So $1$ complete wave will take $=0.002\times 2=0.004sec$

So the time period of wave is $0.004sec$

We can write speed of sound $=\lambda /T$
$=0.002/0.004$
$=0.5cm/sec$.