A sound wave has a frequency of 4 kHz and wavelength 40 cm. How long will it take to travel 1.6 km?

Given, Frequency, ν = 4 kHz = 4000 Hz

Wavelength, λ = 40 cm = 0.40 m

We know that speed, V of the wave = wavelength × frequency

V = λ ν = 0.40 m × 4000 Hz = 1600 m/s

The time taken by the wave to travel a distance, d of 1.6 km is

$\mathrm{t}=\frac{\mathrm{d}}{\mathrm{V}}=\frac{1.6\times 1000 \mathrm{m}}{1600 \mathrm{m}/\mathrm{s}}=\frac{16}{16} \mathrm{s}=1 \mathrm{s}$