How far away are the fish?

Question

A sound pulse emitted underwater reflects off a school of fish and is detected at the same place 0.25 s

 later (see the figure below). How far away are the fish? (Assume the water temperature is 20°C.)

Answer 1

The speed of sound in water at a temperature of 20⁰ C is:

1. Fresh water ... ≈ 1,481 m./s.
2. Sea water ... ≈ 1,522 m./s.

The problem states that it takes the sound wave to 0.25 s.

distance = rate * time

Since the problem did not state in which kind of water this was done, we shall solve the problem for both cases:

1. Case I - Fresh Water:
2. distance = rate * time
3. distance = ( 1481 m./s. ) * ( 0.25 s. )
4. distance = 370.25 m.
5. distance ≈ 370 m.
6. Case II - Sea Water:
7. distance = rate * time
8. distance = ( 1522 m./s. ) * ( 0.25 s. )
9. distance = 380.5 m.
10. distance ≈ 380 m.