Bell Work: Goal Setting
Locate your goal sheet from January.
2. Pick up a new goal sheet by the basket.
3. Fill in your area averages on the goal sheet from
the orange sheet.
4. 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
1.
Vibrations and
Waves
Waves carry energy from one place to
another
 Waves temporarily disrupt the medium
through which they travel

Energy is transmitted (moved) – matter is
NOT transmitted
 Two categories: mechanical and
electromagnetic

Electromagnetic Waves
 do
not need matter
 perpendicular electric and magnetic fields

Radio, microwave, infrared (heat), visible light,
ultraviolet, x-ray, gamma ray
Mechanical Waves
need matter to travel
 Cannot travel through a vacuum

Longitudinal Waves



AKA compressional waves
matter vibrates same direction as the wave moves
(parallel)
Examples: Sound is created from vibrating
objects; AC current
Transverse Waves

matter moves at a right
angle to the movement
of energy
(perpendicular)
– Examples: guitar string,
stadium waves
 video
Practice
Surface Waves
Surface wave: mixture of both Longitudinal and
Transverse; matter travels in circles

Example: water waves

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.

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

Transverse Wave
Anatomy
crest
crest
amplitude Matter
moves
wavelength
Rest line
Energy moves
λ
trough
Practice
trough
Bell Work: Which wave?
Which wave has the. . .
A
1. . . most energy?
B
2. . . smallest
C
wavelength?
3. . . . . . smallest
D
frequency?
4. . . . . smallest amplitude?
Which two waves have the same. . . .
5. . . . . .amplitude?
6. . . . . wavelength?
Wave Properties
property
symbol
Unit
Period
T
s
frequency
f
Hertz(Hz)
wavelength λ (lambda)
m
Speed
v
m/s
amplitude
-------Measuring Wave Properties
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

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
Shock Wave
http://observe.phy.sfasu.edu/courses/phy101/lectures101/
Sonic Booms

http://www.physics.sfasu.edu/astro/courses/
phy101/SonicBoom.html
What determines the speed of a
wave?
(a) the frequency
(b) the wavelength
(c) the amplitude
(d) the period
(e) the medium of transmission
What dictates the frequency of a
sound wave?
(a) wavelength
(b) medium
(c) source of the sound
(d) speed
(e) amplitude
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.
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.