A hiker shouts toward a vertical cliff 481 m away. The echo is heard 3.0 s later. The wavelength of the sound is 0.9 m. What is the frequency?

Group of answer choices

541 Hz

1,671 Hz

357 Hz

1,357 Hz

1 answer

To find the frequency of the sound, we first need to determine the speed of sound using the time it takes for the echo to return.

  1. Calculate the total distance the sound travels: Since the hiker is shouting towards a cliff and waiting for the echo to come back, the sound travels to the cliff and then back to the hiker. Thus, the total distance traveled by the sound is: \[ \text{Total Distance} = 2 \times \text{Distance to Cliff} = 2 \times 481 , \text{m} = 962 , \text{m} \]

  2. Determine the speed of sound: The total time for the echo to return is 3.0 seconds. Therefore, the speed of sound can be calculated as: \[ \text{Speed of Sound} = \frac{\text{Total Distance}}{\text{Time}} = \frac{962 , \text{m}}{3.0 , \text{s}} \approx 320.67 , \text{m/s} \]

  3. Calculate the frequency using the relationship between speed, frequency, and wavelength: The formula relating speed (v), frequency (f), and wavelength (λ) is: \[ v = f \times \lambda \] Rearranging for frequency gives: \[ f = \frac{v}{\lambda} \] Substituting the calculated values into this equation: \[ f = \frac{320.67 , \text{m/s}}{0.9 , \text{m}} \approx 356.3 , \text{Hz} \]

  4. Select the closest answer choice: The closest answer to 356.3 Hz in the provided options is 357 Hz.

Therefore, the frequency of the sound is approximately 357 Hz.