A boy hears an echo of his own voice from a distant hill after `1 s`. The speed of sound is `340 m//s`. What is the distance of the hill from the boy ?

Explanation

Here, speed of sound, `v = 340 m//s`
time taken for hearing the echo, `t = 1 s`
If `d` is the distance between the hill and the boy, total distance travelled by the sound in going and coming back `= 2 d`
As distance travelled by sound = speed of sound xx time.
`2 d = v t` or `d = (vt)/(2) = (340 xx 1)/(2) = 170 m`.