Question

A pendulum has a frequency of 5 vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears echo from the cliff after 8 vibrations of the pendulum. If the velocity of sound in air is 340 ms−¹, find the distance between the cliff and the observer.

Answer 1

Speed of sound in air v = 340 m/s⁻¹

Time taken for 8 vibration t = `8/5` sec

The distance between the cliff and the observer:

d = `(vt)/2`

= `(340 xx 8)/(2 xx 5)`

= 272 m