A boy standing some distance from the foot of a tall cliff claps his hands and hears an echo 0.5s later. If the speed of sound is 340ms−1 − 1 , how far is h...

A boy standing some distance from the foot of a tall cliff claps his hands and hears an echo 0.5s later. If the speed of sound is 340ms−1 ${}^{-1}$, how far is he from the cliff?

Answer Details

V = 2dt $\frac{2d}{t}$ 
v = 340ms−1 ${}^{-1}$
t = 0.5s
d= ?

d = 2d2=340×0.52 $\frac{2d}{2}=\frac{340\times 0.5}{2}$ = 85m