1. Mechanical Waves

2. What is a mechanical wave?
A disturbance in matter that carries energy from one place to another.
Require a material to pass through called a medium.
A medium can be a solid, liquid, or a gas.
3 types of mechanical waves.
1. Transverse waves
2. Longitudinal waves
3. Surface waves

3. Transverse waves
Cause the medium to vibrate at right angles to the direction of wave motion.
Wave motion Slinky motion

4. Parts of a transverse wave
wavelength
Rest position
node
wavelength

5. Trough – the bottom of a wave.
Crest – the top of a wave.
Trough – the bottom of a wave.
Wavelength – the distance from crest to crest or trough to trough.
Node – where the wave intersects the rest position.
Amplitude – distance from the rest position to a crest or trough – measures energy.
Frequency – how many times the wave cycles in a given time period.
Usually measured in Hertz (Hz) – cycles per second
Low frequency
High frequency

6. Wavelength and Frequency
These 2 are related
As one increases, the other decreases.
Low frequency, large wavelength
High frequency, small wavelength

7. Longitudinal Waves Compression waves
Move the medium the same direction as the wave.
Made from compressions and rarefactions
Wave motion
Slinky motion

8. Surface Waves Travel along the surface separating 2 media.
Ocean waves travel between water and air
Have characteristics of both longitudinal and transverse waves.
Transverse part causes up and down motion.
Longitudinal part causes back and forth motion.

9. Wave Speed Speed = frequency X wavelength n f l n = speed (m/s)
f = frequency (Hz)
l = wavelength (m)