Question

answer this.........

Answer 1

We have,

Speed = distance/time

echoed sound is heard 
∴2(distance) = time * speed

⇒distance = 3 * 342/2

⇒ distance = 1026/2 = 513 m

i.e distance of reflecting surface from the source is 513 meters.

Answer 2

Hi there !!

Time = 3sec
Speed of sound = v = 342 m/s

d = distance of the reflecting surface from the source

As the sound reflects back , total distance traveled by echo = 2d

Here is a formula to calculate the distance :

2d = v × t

2d = 342 × 3

2d = 1026 m

d = 1026 ÷ 2

d = 513 metres

Hence ,

distance of the reflecting surface from the source = 513 metres