Question

A pendulum has a frequency of 4 vibrations per second. An observer starts the pendulum and fires a gun simultaneously. He hears the echo from the cliff after 6 vibrations of the pendulum. If the velocity of sound in air is 340 m/s, find the distance between the cliff and the observer.

Accepted Answer

Answer

Since, a pendulum has 4 vibrations in 1 s.

For 6 vibrations,

t = 6/4 = 3/2 = 1.5 s

V = 2d/t

340 = 2d/1.5

d = (340 × 1.5)/2 = 255 m