1. Sound
Chapter 47

2. Sound Sound is a form of energy. Sound is caused by objects vibrating.
Example Tuning Fork, Guitar String

3. Sound Sound needs a medium to travel. Sound cannot travel in a vacuum.
Eg Air, Water, Solids.
Sound cannot travel in a vacuum.

4. Reflection of Sound
Sound bounces back of solid surfaces this called an echo.
Bats use this principle to avoid obstacles.

5. Ultrasound
Ultrasound is a very high pitched sound (Note/Frequency) which cannot be detected by human ears.
Uses of Ultrasound:
Ships detecting depth
Medicine (viewing embryos)

6. Speed of Sound Sound travels in air at 340m/s.
Sound travels faster in water (1,400m/s) and fastest in solids (5,000m/s).
Light is a lot faster than sound it travels at 300,000,000m/s.

7. Measuring Sound Sound is measured in decibels (dB).
0 is the lowest sound that can be heard, anything above 85dB is dangerous for our ears.
Protection for ears must be worn when working with loud machinery