Question:
Why do we hear the sound produced by the humming bees while the sound of vibrations of pendulum is not heard?
Solution:
This is because the frequency of sound produced by humming bees lies in audible range $(20 \mathrm{~Hz}$ to 20,000
$\mathrm{Hz}$ ) and frequency of the sound of vibrations of pendulum lies in infrasonic region. ( $1 \mathrm{~Hz}$ to $19 \mathrm{~Hz}$ )