SOUND

Sound is a very weak form of energy, orginating from a source that is moving back and force (vibration) rapidly. As long as the substance is vibrating, the sound may be heard. As soon as the vibration stops, so does the sound.

3.5 million people would have to talk steadily for 30 minutes in order to heat up a cup of tea.

Sound waves??? Have you heard of waves before...? water waves, radio waves, microwaves, electromagnetic waves! So what do all waves have in common? A wave is a disturbance that transmits energy as it travels through matter. The energy of the wave moves throught the matter...or the medium (water, air gases etc). Scientists often describe waves using the following terms:


1) crest = highest points
2) trough = lowest point
3) wavelength = distance from one crest to the next crest
4) amplitude = one-half the height of the wave from the crest of the wave to the trough

In sound, the more waves per second (frequency), the higher the pitch and as the number of wavelengths produced decreases the pitch gets lower. The higher the amplitude the greater the amount of energy in the sound wave and the louder the sound. If the frequency (# of vibrations per second) is too high or too low, then we cannot hear the sound. Most humans hear sounds between 20 and 20,000 vibrations per second or Hertz.


Why is it that in space, sound cannot travel and sound cannot be heard? (THINK, then CLICK)
























SOUNDS OF SILENCE
When a substance vibrates, the a sound is transmitted in all directions in invisible sound waves. A medium of molecules and at least one vibration is needed in order to make one sound wave. If there are no molecules to continue the vibration from the source, then sound cannot be transmitted. In space where there are no molecules, sound cannot travel.