A sound wave has frequency of 3 kHz and a wavelength 45 cm. How long will it take to travel 1.8 km?

Given, frequency, V = 3 kHz = 3 X ${{10}^{3}}$ Hz

Wavelength, X = 45 cm = 45 X ${{10}^{-2}}$ m

From the relation, speed of wave, v = v$\lambda $

= 3 x ${{10}^{3}}$ x 45 x ${{10}^{-2}}$ = 1350m${{s}^{-1}}$

Distance to be covered =1.8 km = 1.8 X 1000 = 1800 m

.’. Time taken by the wave to cover the distance of 1.8 km = Distance/Speed = 1800/1350 = 1.33s