Question

A man stands between two parallel cliffs (not in middle). When he claps his hands, he hears two echoes one after 1 second and the other after 2 seconds. If the velocity of sound in air is 330 ms1, the width of the valley is

Answer 1

Break up the 2 echoes into 2 parts.

Part 1: using the formula 2d=vt, where v= the speed of sound, 330m/s, t= time taken and d = distance, plug in the given values into the formula and you get d= 330m. Part 1 is done!

Part 2 : do the same for this, see the above. ( you'll get d= 660m)

So, 330m is the distance from the shooter and the cliff, which reflected the sound wave to produce the 2s echo, while 660m is the distance from the shooter and the other cliff, which reflected the sound wave to produce the 4s echo. The distance between the cliffs is the sum of the distances which you found.