Question

A person is standing $1km$ away from a source of sound. The velocity of sound in the medium is $340m{s}^{-1}$. Calculate the number of oscillations (approximately) that the sound wave makes before it reaches that person. The frequency of the sound is $500Hz$.

• A. 1450
• B. 1417
• C. 1470
• D. 340

Answer 1

The correct option is C 1470

Given:
Distance between source and observer, $s=1000m$
Velocity of sound, $v=340m{s}^{-1}$
Frequency of sound, $f=500Hz$

Time taken for the sound wave to reach the observer from the source is:
$t=\frac{s}{v}$

Number of oscillations in $1s$ is the frequency, $f$
Number of oscillations in time $t$ will be:
$n=tf$
$n=\frac{s}{v}f$
$n=\frac{1000\times 500}{340}$
$n\approx 1470$