3seconds after a gun is fired, the person who fired the gun hears an echo. How far away was the surface that reflected the sound of the shot? (book answer is 510m)

speed of sound 340m/s
time = 3seconds

dont know what to do

2 answers

how far does sound travel in 3 seconds?

distance=340*3/2
In order to find how far the surface, you have to divide the speed of sound with the time taken to hear the echo. 340 m/s divided by 3 s is 1020m/s. However, since the sound is reflected, the distance should be divided by 2. You'll get 510m.