1. Wave Period Amplitude Crest Trough Frequency Hertz Wavelength
Please use your own sheet of paper to define the following vocabulary terms:
Wave
Period
Amplitude  
Crest 
Trough
Frequency
Hertz
Wavelength
Transverse wave
Longitudinal wave

2. Mechanical Waves

3. What are mechanical waves? What do you think waves carry?
Can you see waves? Examples?

4. Mechanical Waves
Mechanical waves are disturbances in matter that carry energy from one place to another.
Usually require matter through which to travel
The matter a wave travels through is called a medium.
Medium can be a solid, liquid, or gas
Some waves can travel through space…with no medium!

5. How are mechanical waves created?

6. Creation of mechanical waves:
Need a source of energy!
That energy causes a vibration to travel through the medium

7. Types of Mechanical Waves
Transverse:
A wave that causes the medium to vibrate at right angles to the direction of the wave

8. Parts of a transverse wave:

9. Types of Mechanical Waves, ctd.
Longitudinal:
A wave in which the vibration of the medium is parallel to the direction the wave travels

10. Parts of a longitudinal wave:

11. Remember!
A wave doesn’t move the medium…it’s just energy traveling through the medium!

12. Transverse and Longitudinal Wave Which is which?

14. Period vs Frequency
Period – (T) – The time it takes for one cycle (= how long?)
Measured in seconds
Frequency – (f) – The number of cycles in a given time (= how many?)
Measured in Hertz (Hz)
Frequency is the inverse of the Period
f = 1 / T

15. Speed of a wave We find speed by distance divided by time.
The same holds true for waves!
Speed of a wave = Wavelength/Period
Speed of a wave = Wavelength*Frequency

16. Speed of a Wave The speed of a wave is constant within a medium.
The speed can change when a wave enters a new medium
All waves of the same type travel at the same speed
This means wavelength is inversely proportional to frequency!
If the wavelength increases the frequency has to decrease!
If the wavelength decreases the frequency has to increase!

17. Practice Problem #1
A wave in a spring has a wavelength of 0.1 meters and a period of 0.2 seconds. What is the speed of the wave?

18. Practice Problem #2
Find the wavelength of a wave in a rope that has a frequency of 2.0 Hz and a speed of 0.4 meters/second.