identify the following parts of a wave: 1. a to e 2. b 3. d 4. the line connecting a and g 5. the...
TRANSCRIPT
Identify the following parts of a wave:1. A to E2. B3. D4. The line connecting A and G5. The distance from F to the line
Do Now (6/1/12): Happy Friday!
Exam Review: Please use the rest of class to work on your
review packet. Not working on your packet will result in a
loss of 2 points for today!!! If you have any questions or need any
slides, please ask.
Several positions along the medium are labeled with a letter. Categorize each labeled position along the medium as being a position where either constructive or destructive interference occurs.
Do Now: 4/5
A hiker shouts toward a vertical cliff 589 m away. It takes 3.1 s to reach the cliff. The wavelength is 0.65 m.
1. What is the speed of sound in air?
2. What is the frequency? 3. What is the period of the wave?
Do Now 4/5
Periodic motion is motion that repeats itself in a regular cycle. List three examples of periodic motion in your life.
Do Now (3/26/12):
Waves3/26/12
Last week before spring break!
Wave: a disturbance that carries energy or matter through space
Pulse: a single disturbance
Periodic wave: a repeated wave
Waves
Mechanical waves: require a material medium to travel (air, water, ropes)
Electromagnetic waves: do not require a medium to travel (light, radio)
Types of Waves:
1.Transverse: medium moves perpendicular to the direction of the wave.
Mechanical Waves
2. Longitudinal: medium moves parallel to the direction of the wave
Mechanical Waves
3. Surface: combination of transverse and longitudinal
Mechanical Waves
Crest: highest point Trough: lowest point Wavelength: shortest distance between
crests and troughs; represented by Greek letter λ (lambda); measured in m or nm
Wave Characteristics
crest
trough
Equilibrium: the position at which the net force is zero
Amplitude: the distance from a crest to where the wave is at equilibrium
Wave Characteristics
Equilibrium position
Period (T ) – time to complete one cycle of periodic motion; measured in seconds (s)
Frequency (f )– # of complete cycles per second; measured in Hertz (Hz)
Wave Characteristics
sHz
Tf
11
1
A radio wave has a frequency of 93.9 MHz (93.9 * 106 Hz). What is its period?
Example:
f = 93.9 * 106 Hzf = 1 / TT = 1 / f
T = 1 / 93.9 x 106 HzT = 1.06 x 10-8 s
Wavelength – super important!!!
f
v
A sound wave has a frequency of 200 Hz and travels the length of a football field(91.4 m) in 0.3s.
a. What is the speed of the wave?
b. What is the wavelength of the wave?
c. What is the period of the wave?
Example:
sms
m
t
dv /6.304
3.0
4.91
msm
f
v52.1
200
/6.304
sf
T 005.0200
11
Use the rest of class to work on the paper: Introduction to Waves. It is due on Wednesday!!!!!
Don’t forget…. Final mouse trap testing is on THURSDAY, MARCH 29!!!
Practice:
Identify the following parts of a wave:1. A to E2. B3. D4. The line connecting A and G5. The distance from F to the line
Do Now (3/27/12):
Use the rest of class to work with the slinkys.
IF YOU TANGLE A SLINKY SO THAT IT NO LONGER WORKS, YOU WILL LOSE POINTS ON YOUR LAB!!!!
REMINDER: Homework is due tomorrow!
Slinky Lab:
Review:
crest
trough
Equilibrium position
sHz
Tf
11
1
A sound wave travels across a football field at 330 m/s. The wavelength is 1.12 m.
1.What is the frequency?
2.What is the period?
Do Now (3/28/12):
From your calculations yesterday, did the size of the pulse have any affect on the speed?
Slinky Lab
Two methods:
THE SPEED OF A WAVE DEPENDS ONLY ON THE MEDIUM!!!
Speed of a wave:
fv t
dv
phenomenon that occurs when two waves meet while traveling along the same medium
Wave interference:
occurs at a location along the medium where two interfering waves have a displacement in the same direction
Constructive interference:
Positive or negative
Constructive Interference
occurs at a location along the medium where two interfering waves have a displacement in the opposite direction
Destructive interference
Equal sized opposite pulses result in a straight line:
What if we have one of each???
Subtract:
What if they are not equal?
They pass through each other:
What happens after they interfere?
When two waves interfere, the resulting displacement of the medium at any location (the AMPLITUDE) is the algebraic sum of the displacements (the AMPLITUDES) of the individual waves at the same location.
The Law of Superposition
Write your name and class period
On the paper on your desk:
Categorize each point as constructive or destructive:
Example:
Classroom textbook p.347 problem 45
4 min!!
Practice (on same sheet of paper):
Take out your mousetrap car and wait quietly for further instructions.
Do Now (3/29/12):
Use the rest of class to work on the paper “Wave Superposition.” It is due on Friday!!!
You can turn this paper in by the end of class for EXTRA credit!!!
If you need to, you may meet with your mousetrap car group.
Practice:
1. Initial proposal – already due 2. Proof of vehicle moving (photo or
video) – already due3. Mousetrap lab (emailed and one
per group) – already due 4. Final mousetrap analysis
questions; (you will get these today) one per group; due tomorrow
5. Mousetrap car results (you will do today)
Components of Project:
1. What is interference?2. What are the two types of
interference?3. What is the difference between
the two types?4. What does the Law of
Superposition state? Happy Day Before Spring Break
Do Now (3/30/12):
Do Now’sSlinky Labs *(if you have not already)
Superposition paper (*if you have not already)
Mousetrap Analysis Questions *(if you have not already)
Please Pass In:
Slinky Lab!!!!!
1.What was your favorite thing you did over spring break?
2.What is one goal you have for the fourth quarter?
Do Now (4/11/12):
1.Slinky Lab Part 2
Please Pass In:
Complete the Unit 2, Worksheet 5. This is your quiz review.
If you finish before the end of class, please turn it in.
If not, you will have to finish for homework.
You will have a quiz on Friday on Wave Properties!
Review:
An incident pulse travels towards a fixed end. What do you think will happen once the pulse reaches the end?
Do Now (4/12/12): (2 min)
A sound wave has a frequency of 200 Hz and travels the length of a football field(91.4 m) in 0.3s.
a. What is the speed of the wave?
b. What is the wavelength of the wave?
c. What is the period of the wave?
Do Now (4/13/12:
sms
m
t
dv /6.304
3.0
4.91
msm
f
v52.1
200
/6.304
sf
T 005.0200
11
Do Now’sHomework – (Waves Unit 2, Worksheet 5)
Wave simulation (if completed)
You have until MONDAY to finish your simulation questions
Pass in:
1. A single disturbance that moves through a medium is_________.
2. The speed of a wave is determined by its_____.
3. The process used to predict the effect of combining two waves as they pass through the same medium is called ____________.
4. Sound waves emanate from a razor at a rate of 50 cycles per second and spread out at 340 m/s. the frequency is___________.
Do Now (4/19/12): Fill in the blank
Complete ONE brainstorm idea for your project and get it initialed by Ms. Timson
Once your brainstorm has been initialed, work on your review sheet.
Reminder: you have a test next Tuesday!!!
Class Agenda:
1. Is a sound wave mechanical or electromagnetic?
2. Is a sound wave transverse or longitudinal?
3. What does a sound wave NOT travel through?
4. What unit is used to measure the loudness of sound?
5. What unit is used to measure the pitch of sound?
Do Now (4/20/12):
Use the rest of class to complete the analysis
Analysis:
Wave Behavior
Clear your desks of everything except your Do Now Sheet and get ready for a POP QUIZ
Do Now:
APRIL FOOLS!!!!!
!!
Boundary: the divide between two different media
Medium: the substance through which a wave travels
Waves at Boundaries
incident pulse: wave approaching the boundary
reflected pulse: the disturbance that returns after bouncing off the boundary
transmitted pulse: the disturbance transmitted to the next medium
Waves at Boundaries
1. What is the difference between constructive and destructive interference?
2. What does the Law of Superposition state?
Real Do Now:
The transmitted pulse (in the more dense medium) is traveling slower than the reflected pulse (in the less dense medium).
The transmitted pulse (in the more dense medium) has a smaller wavelength than the reflected pulse (in the less dense medium).
The speed and the wavelength of the reflected pulse are the same as the speed and the wavelength of the incident pulse.
Less dense to more dense
The transmitted pulse (in the less dense medium) is traveling faster than the reflected pulse (in the more dense medium).
The transmitted pulse (in the less dense medium) has a larger wavelength than the reflected pulse (in the more dense medium).
The speed and the wavelength of the reflected pulse are the same as the speed and the wavelength of the incident pulse.
More dense to less dense
In phase: the same two points on a wave:examples: A&E, B&F, C&G
Out of phase: two points that are not the sameExamples: A&C, E&G
In Phase