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 remain the same. Do you hear echo sound on a hotter day ?

Explanation

The minimum distance (d) for the distinct echo to be heard (say at `22^@ C`) is `17.2 m` (as `2 d = v t = 344 xx 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//s` and as such `2 d = 356 xx 0.1 = 35.6 m` or `d = 17.8 m`. Thus, if the distance of the reflecting surfece 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 noe required is `17.8 m`.