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Sound waves are created by the vibration
of some object or even air itself. They can be created
by a back-and-forth motion of an object, by having air
pass over a vibrating object, or by moving air causing
the vibrations.
Questions you may have about sound are:
-
How is does a vibrating object
create sound?
-
What is an example of sound created
by air passing by a vibrating object?
-
How can air cause its own
vibrations?
A vibrating object will cause these
compression waves in air or another medium.
A good example is a tuning fork. The
metal rods in the tuning fork move back-and-forth,
causing the compression wave in the air. A tuning fork
could also be put in water, creating sound waves within
the water.
Note that the waves created by the
tuning fork on the surface of a pool of water are not
sound waves. They are surface waves, which are circular
instead of compression waves.
Other examples of something vibrating
back-and-forth to cause sound are a guitar string, drum,
loudspeaker.
If something vibrates as air passes
through or by it, the air can be also made to vibrate as
sound waves. The best example of that method come from
your vocal chords.
The air causes some of the vibration and
the vibration then amplifies the sound. You can see this
by putting a thick blade of grass between your thumbs
and blowing on it. Another example is wrapping a comb in
wax paper, putting it up to your mouth and blowing on it
to make the noise, similar to a kazoo.
When moving air passes an by object, it
can start some air to vibrate and make sound. This type
of sound can be heard on a windy day or when you blow
across the top of a bottle.
An explosion causes a sudden surge in
air, causing the high-volume sound. Thunder and a
balloon popping are examples of this way of creating
sound.
Sound can be created by a back-and-forth
motion of an object, by having air pass over a vibrating
object or by moving air causing the vibrations. |
