Question

A source moves towards a stationary observer with a speed of 10m/s. If the frequency of the source is 10Hz what will be the wavelength of sound heard by the observer? Speed of sound = 330m/s

• A. 33m
• B. 32m
• C. 34m
• D. 31m

Answer 1

Answer: (B)

32m

Answer 2

The wavelength ($\lambda_o$) heard by the observer is given by the formula:

$$\lambda_o = \frac{v - v_s}{f_s}$$

Where:

• $v$ is the speed of sound in the medium (330 m/s)
• $v_s$ is the speed of the source (10 m/s)
• $f_s$ is the frequency of the source (10 Hz)

Substituting the values:

$$\lambda_o = \frac{330 \text{ m/s} - 10 \text{ m/s}}{10 \text{ Hz}} = \frac{320 \text{ m/s}}{10 \text{ Hz}} = 32 \text{ m}$$

Thus, the wavelength of sound heard by the observer is 32m.