1. Bell Work: Goal Setting
Locate your goal sheet from January.
Pick up a new goal sheet by the basket.
Fill in your area averages on the goal sheet from the orange sheet.
Fill out the rest of the goal sheet. Remember to choose specific and realistic things to do to improve your grade.
Ex: Do review sheet as a practice test; review bell work 2x a week; study with a partner for 30 minutes; answer all lab questions; turn in on time

2. Vibrations and Waves

3. Waves carry energy from one place to another
Waves temporarily disrupt the medium through which they travel

4. Energy is transmitted (moved) – matter is NOT transmitted
Two categories: mechanical and electromagnetic

5. Electromagnetic Waves
do not need matter
perpendicular electric and magnetic fields
Radio, microwave, infrared (heat), visible light, ultraviolet, x-ray, gamma ray

6. Mechanical Waves
need matter to travel
Cannot travel through a vacuum

7. Longitudinal Waves AKA compressional waves
matter vibrates same direction as the wave moves (parallel)
Examples: Sound is created from vibrating objects; AC current

8. Transverse Waves video
matter moves at a right angle to the movement of energy (perpendicular)
Examples: guitar string, stadium waves
video
Practice

9. Surface Waves
Surface wave: mixture of both Longitudinal and Transverse; matter travels in circles
Example: water waves

10. Wave Speed SPEED DEPENDS ONLY ON THE MEDIUM
Medium is the stuff that the wave travels through – spring, space, air, iron, 55o F water, etc.

11. Wave Speed
Sound waves move at 343 m/s in room temperature air, faster in liquids and solids
Electromagnetic waves travel at speed of light c = 3 x 108 m/s; slower through matter

12. Transverse Wave Anatomy
crest
crest
amplitude
Matter moves
wavelength
Rest line
Energy moves
trough λ
trough
Practice

13. Bell Work: Which wave? Which wave has the. . . 1. . . most energy?
. . smallest
wavelength?
smallest
frequency?
smallest amplitude?
Which two waves have the same amplitude?
wavelength?
A B C D

14. Wave Properties property symbol Unit Period T s frequency f Hertz(Hz)
wavelength
Speed
amplitude
----
-----
property
symbol
Unit
Period T s
frequency f
Hertz(Hz)
wavelength
λ (lambda) m
Speed v
m/s
amplitude
----
-----
property
symbol
Unit
Period T s
frequency f
Hertz(Hz)
wavelength
λ (lambda) m
Speed
amplitude
property
symbol
Unit
Period T s
frequency
wavelength
Speed
amplitude
----
-----
property
symbol
Unit
Period
frequency
wavelength
Speed
amplitude
----
-----
Measuring Wave Properties

15. Wave Relationships
as wavelength increases, frequency decreases (inversely related)
As wavelength increases, period increases (directly related)
As frequency increases, period decreases (inversely related)
Speed only depends on the medium that a wave travels through
Energy is shown in the amplitude

16. If a water wave oscillated up and down three times each second and the distance between wave crest is 2 m, what is its frequency?
Answer: 3 Hz
What is its period?
Answer: 1/3 second
What is its wavelength?
Answer: 2 m
What is its wave speed?
Answer: 6 m/s

17. Shock Wave

18. Sonic Booms

19. What determines the speed of a wave?
(a) the frequency
(b) the wavelength
(c) the amplitude
(d) the period
(e) the medium of transmission

20. What dictates the frequency of a sound wave?
(a) wavelength
(b) medium
(c) source of the sound
(d) speed
(e) amplitude

21. Examples of Resonance mass on a spring at resonance
swinging your legs in a swing
breaking a wine glass using sound
a singing rod caused by forced vibration
fog horn
a tuning fork exciting a guitar string
In 1940, the Tacoma Narrows Bridge was destroyed by wind-generated resonance.

22. Tacoma Narrows Bridge
Resonance allows energy to be transferred to a vibrating object efficiently if the energy is delivered at the natural frequency of vibration.