1. Sound Waves
You Have to Hear This!!!!

2. Like all waves, sound waves are produced by a vibration.
Producing a Sound Wave
Like all waves, sound waves are produced by a vibration.
A tuning fork vibrates to produce a sound.
A guitar string vibrates to produce a sound.
Your vocal cords vibrate to produce a sound.
A tree that falls in the woods causes a vibration and produces a sound– even if no one is around to hear it!!!!!!!

3. Properties of Sound Waves
Sound Waves are Longitudinal Waves. As the fork moves forward and back it alternately compresses and then decompresses the air (or whatever medium it is traveling through). From above the source it looks more like this:

4. Properties of Sound Waves
Sound Waves are Mechanical Waves This means they MUST have a medium (matter) to travel. This means sound waves CANNOT travel through empty space ( a vacuum).

5. Properties of Sound Waves
All sound travels at the same speed in the same medium. This speed is called the speed of sound. The speed of sound in air is : 343 m/s (767 mph) The speed of sound in water: 1433 m/s (3206 mph) The speed of sound in concrete: 3400 m/s (7606 mph) The speed of sound in steel: 6100 m/s (13645 mph)

6. Properties of Sound Waves
The speed of sound is also affected by temperature.
Basically, the higher the temperature the faster sound travels.
As an equation this looks like this:
vsound = Tc

7. The Doppler Effect
Whenever a source of sound is moving, the pitch you hear depends on whether the sound source is moving towards you or away from you.