Question

A person is standing 1 km away from a source of sound. If the velocity of sound in the medium is 340 m/s, then calculate the number of oscillations (approximately) that the sound wave makes before it reaches that person. The frequency of the sound is 500 Hz.

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

Answer 1

The correct option is C

1470

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

Time taken by the sound wave to reach the observer from the source = $\frac{d}{v}=\frac{1000}{340}=2.94sec$

Now, the frequency of sound wave is 500 Hz, i.e.

In one second, the wave makes 500 oscillations

In 2.94 seconds, the sound wave will make (2.94 x 500) oscillations.

Thus, the correct answer = 2.94 x 500 = 1470 oscillations.