Question

A woman standing before a cliff claps her hands, 3.6s later she hears the echo. How far away is the cliff? The speed of sound in air at ordinary temperature is 353m/s.

Answer 1

Since we know that the time it takes to the cliff will be half the time it takes for the echo to be heard, the distance is:

`t=(3.6s)/(2)\Rightarrow t=1.8s`
`d=(353m)/(s)\cdot1.8s\Rightarrow d=635.4m`

So, the cliff is 635.4 meters away.