Soon

Speed ​​of sound


Sound propagation is not instantaneous. We can verify this during storms: thunder hits our ears seconds after lightning, although both phenomena (lightning and thunder) form at the same time.

The propagation of light, in this case lightning, is not instantaneous either, although it is faster than sound.

Thus, the sound takes some time to travel a certain distance. In addition The speed of its propagation depends on the medium in which it propagates and the temperature at which it is present.

In air, the temperature of 15ºC the speed of sound is about 340m / s. This speed varies by 55cm / s for each temperature degree above freezing. At 20ºC, the speed of sound is 342m / s, at 0ºC it is 331m / s.

In water at 20ºC, the speed of sound is approximately 1130m / s. In solids, the speed depends on the nature of the substances.

Physiological qualities of sound

At all times we distinguish the most different sounds. These differences our ears perceive are due to the physiological qualities of sound: height, intensity and timbre.
Height - even without knowing music, it is easy to distinguish the high (or thin) sound of a violin from the low (or thick) sound of a cello. This quality that makes it possible to distinguish a low sound from a high sound is called.

Thus, it is often said that the sound of the violin is loud and that of the cello is low. The pitch of a sound depends on the frequency, ie the number of vibrations per second. The higher the frequency, the higher the sound and vice versa. In turn, the frequency depends on the length of the vibrating body and its elasticity. The greater the attraction and the shorter the guitar string, for example, the sharper the sound it makes.


You can also notice the frequency difference using a comb that has thin and thick teeth. Passing the comb teeth on the end of a card you will hear two types of sound from the card: the high-pitched sound produced by the thin teeth (higher frequency) and the low-pitched sound produced by the thicker teeth (lower frequency).