More precisely, it propagates four times faster in water than in air. You know when you pull a rubber band around the edges? The speed with which it vibrates is much greater than if it were done with a string, isn’t it? With sound more or less the same thing happens. What a sound source does is compress the nearest mass of air or water into a smaller volume. Then the medium reacts: it expands again and collides with the nearest molecules, which then repeat the process. It is this “stretch-and-pull” that makes the sound walk. “Since the sound wave is transmitted by compression and decompression, its speed basically depends on the elasticity of the medium”, says physicist Cláudio Furukawa, from USP. As water, when compressed, reacts much faster than air (that is, it has more elasticity), the speed of sound waves is greater inside it.
The speed of sound in water was determined to be 1435 m/s during experiments carried out in a lake in Switzerland by physicists Jacques Sturm, French, and Daniel Colladon, Swiss, in 1826. In air, at sea level, this speed is around 331 m/s.
Two means, two measures
Speed of sound in water is four times faster than in air
SOUND BARRIER IN THE ATMOSPHERE
A supersonic plane, like the Concorde below, needs a speed of around 1190 km/h to break the sound barrier. Or rather: so that the plane moves faster than the sound waves it creates in the air.
SOUND BARRIER AT SEA
For a hypothetical super-fast submarine, breaking the sound barrier would be much more difficult: in addition to overcoming the immense resistance of the liquid medium, it would have to go over 5,000 km/h. This velocity increases as salinity, temperature and water pressure increase. At sea, therefore, it varies between 5 220 km/h and 5 652 km/h
– How did the expression take water from the knee?
“Why does water swirl down the drain?”