Answer to Question #88451 in Molecular Physics | Thermodynamics for gc

Question

A sound pulse emitted underwater reflects off a school of fish and is detected at the same place
0.15 s
later (see the figure below). How far away are the fish? (Assume the water temperature is 20°C.)

Answer 1

The double distance 2d from the emitter to the school of fish is equal to the speed of sound in water V_s multiplied by the time between emission and detection of a sound pulse, t=0.15 s

$$2d={{V}_{s}}\cdot t$$

In fresh water, sound travels at about 1481 m/s at 20 °C (https://en.wikipedia.org/wiki/Speed_of_sound#Water)

Then

$$2d=1481\text{ }m/s\cdot 0.15\,s=222.15\,m$$

$$d=\frac{222.15\,m}{2}\approx 111\,m$$

The school of fish is at a distance of 111 m