SSC CGL (Prelims) GK: Waves and Sound questions with solutions

Q1. How long will a sound wave take to travel 1.5 km, if its frequency is 5 kHz and wavelength is 6 cm?

1. 2.5 seconds
2. 50 seconds
3. 5 seconds
4. 25 seconds

Answer: 5 seconds

The speed of a wave is given by $v=f\lambda$. Here, $f=5000\,\text{Hz}$ and $\lambda=0.06\,\text{m}$, so $v=300\,\text{m/s}$. Time taken to travel $1.5\,\text{km}=1500\,\text{m}$ is $t=1500/300=5$ seconds.