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Question

A sound wave has a frequency of 4 kHz and a wavelength of 25 cm. How much time will it take to travel a distance of 2.5 km?

This question was previously asked in
RRB ALP 2025 CBT 2 Wiremen Question Paper (28-Jul-2026) (Shift 2)
The correct answer is
2.5 s

Sound Wave Travel Time Calculation

Given Information

  • Frequency (\(f\)): 4 kHz = \(4 \times 10^3\) Hz
  • Wavelength (\(\lambda\)): 25 cm = 0.25 m
  • Distance (\(d\)): 2.5 km = 2500 m

Calculations

First, calculate the speed of the sound wave (\(v\)) using the formula:

\(v = f \times \lambda\)

Substitute the given values:

\(v = (4 \times 10^3 \text{ Hz}) \times (0.25 \text{ m})\)

\(v = 1000 \text{ m/s}\)

Next, calculate the time (\(t\)) taken to travel the distance (\(d\)) using the formula:

\(t = \frac{d}{v}\)

Substitute the distance and calculated speed:

\(t = \frac{2500 \text{ m}}{1000 \text{ m/s}}\)

\(t = 2.5 \text{ s}\)

Result

The time taken for the sound wave to travel 2.5 km is 2.5 seconds.

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