Question

If the wavelength of a sound wave is 40 cm and the time period T = 0.005 s, how many seconds will it take to travel 4 km?

• A. 5 seconds
• B. 10 seconds
• C. 20 seconds
• D. 50 seconds

Answer 1

The correct option is D

50 seconds

Given, wavelength = 40 cm = 0.4 m

time period = 0.005 s

Speed of the sound wave, $v=\frac{wavelength}{timeperiod}=\frac{0.4}{0.005}=80m{s}^{-1}$

Now distance to be covered = 4 km = 4000 m

Hence, time taken to cover 4 km = $\frac{distance}{speed}=\frac{4000}{80}=50s$