Question

A boy clapped his hands near a cliff and heard the echo after 4s. What is the distance of the cliff from the person if the speed of the sound, v is taken as 346 ms${}^{-1}$?

• A. 2 m
• B. 1384 m
• C. 692 m
• D. 2768 m

Answer 1

The correct option is C 692 m

Given, Speed of sound, $v=346m{s}^{-1}$ Time taken for hearing the echo, $t=4s$
Distance travelled by the sound $=v\times t=346m/s\times 4s=1384m$
In 4 s sound has to travel twice the distance between the cliff and the person.
Hence, the distance between the cliff and the person $=1384m/2=692m$