question_answer 28)

When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?

Answer:

The minimum distance (d) for the distinct echo to be heard (say at 22°C) is 17.2 m (as 2d = vt = 344 x 0.1 = 34.4 m ). On a hotter day, the temperature increases and the speed of sound in air also increases. For example, at 40°C, speed of sound, i.e. v = 356 m and as such 2d = 356 x 0.1 = 35.6 m or d = 17.8 m. Thus, if the distance of the reflecting surface and the source of sound remains the same (i.e., 17.2 m), no echo is heard on the hotter day as the minimum distance now required is 17.8 m.