05notes.ppt - Oak Ridge Schools by wulinqing

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									 General Physics
           Oak Ridge HS
Mr. M. Perkins • Ms. C.J. Pina
Monday, August 17, 2009
Introductions and Notecards

     Last Name, First Name                                 Period
     Street Address                            Book Number: 09-???
     City, State, Zip
     Your home number
     Your cell phone number
     Your email address
     Your lunch period (4th or 5th)
     Current math class
     Extracurricular activities (sports, music, arts)
     One thing I should know about you is…
Science Autobiographies
 1st Paragraph –
 Tell me about yourself, where you were born, brothers
 and sisters, favorite color, what you want to be when
 you finish high school.

 2nd Paragraph –
 Tell me about your worst experience in science class.
 Please give good details.

 3rd Paragraph –
 Tell me about your best experience in a science class.
 Again, good details, please 
Tuesday, August 18, 2009

* Get out your science notebooks, please.
LAB: Designing an Experiment
 First, set up the Table of Contents
 Next, set up your lab book as follows
   Date in the upper right corner
   Title centered at the top of the page
   Add the following, starting from the left margin below
    the title
    Partners: (the people at your table)
    Objective: To design an experiment to collect and
    analyze data on poppers.
    Materials: (leave blank for now… allow two lines)
    Procedure:
Wednesday, August 19, 2009
Investigate – Setting up your notebook
Investigate - In your notebooks…
 3a) Table – Length of string varies, mass the same
 Answer to 4b)
  Make a general statement about what happens to the pitch
  you hear as you change the length of the vibrating string.

 5a) Table – Mass varies, length of string the same
 Answer to 6b)
  Look over you data. Increasing the mass tightens the string
  and increases its tension. Make a general statement (write a
  sentence) about what happens to the pitch as you change
  the tension on the string.
Physics Talk: Changing the Pitch
To produce sound, something must vibrate.
 You
   observed the vibration of the string as it produced
    sound.
   investigated two of the variables, ___________ and
    ___________ that affect the pitch of the sound
Physics Talk
 Shortening the string (increased / decreased / didn’t
 change) the pitch.

 When you added mass to the mass hanger on the end
 of the string, you (increased / decreased / didn’t
 change) the pitch.

 This is because increasing the mass (increases /
 decreases / doesn’t change) the tension of the string.
Physics Talk
 Combining the two results, you can say that
 (increasing / decreasing) the tension or
 (increasing / decreasing) the length of the string
 will increase the pitch.
Checking Up (p. 487)
1. What happens to the pitch of the sound produced by
   a string when its tension is increased?
2. When you decrease the length of a string in an
   instrument, how does the pitch of the sound you
   hear change?
3. What effect did adding mass to the mass hanger have
   on the string in the Investigate?
4. How is sound produced in a percussion instrument?
What Do You Think Now?
 How do guitarists or violinists today make different
  sounds?
 If someone were pretending to play a guitar (for
  example, the air guitar), how would the player position
  his or her fingers to make the highest pitch notes?

You investigated the effects of changing the length of the
  string and the tension of the string have on the pitch
  of the sound produced.
How do you now think that these musicians make
  sounds with different pitches? Use evidence from your
  investigation to support your answer.
Essential Questions (p.489)
Complete in your science notebooks, then we’ll discuss
  as a class.
 What does it mean?
  A violin is less than 0.5 m long. A bass fiddle is more
  than 1.5 m long. Which instrument do you expect to be
  able to play notes with a lower pitch and why?
 How do you know?
  What experiment can be conducted to demonstrate
  that higher pitch sounds can be produced by either
  shortening the length of a vibrating string or by
  increasing the tension of a vibrating string?
Essential Questions (p.489)
Complete in your science notebooks, then we’ll discuss
  as a class.
 Why do you believe?
  How might the length of the string and the tension of
  the string relate to the properties of the wooden bars
  in these instruments?
 Why should you care?
  List some examples where vibrating strings show up in
  musical instruments. Describe how a drum produces
  sound. How will what you learned in this section help
  you with your challenge of creating sound?
What do you think?
 How does water move to make a wave?
Investigate
PART A: STADIUM WAVE
In your science notebook, answer the following in
  complete sentences
 1a)
 1b)
 1c)
 1d)
Divide and Conquer
Three roles:
 Director – responsible for having the textbook,
  reading it aloud, and giving instructions to the other
  group members.
 Recorder – responsible for writing everything in the
  science notebook and sharing results with the group at
  a later time.
 Worker – responsible for doing what the director tells
  them and telling the recorder what to record.
Investigate
PART B: Producing Transverse Waves on a Spring (1-8)
Complete the following, writing your responses in your science notebooks.

 1a)                                        5a)
 2a)                                        TABLE 6a-b, 7 a-c
 2b)                                        7d)
 2c)                                        Skip 9
 2d)
 2e)
 3a)
Investigate
Periodic Waves (B: 10-15)
Answer the following in your science notebooks
 10a)
 11a)
 11b)
 12a)
 TABLE 13a-b
 SKIP 14
 15a-c)
Investigate
PART C: Producing Longitudinal (Compressional)
  Waves on a Spring
In your science notebook, answer the following in
  complete sentences
 1. Show calculation of the speed of compressional wave
 TABLE 1a)
 1b)
 1c)
 1d)
Investigate
PART D: Using a Wave Viewer
In your science notebook, answer the following in
  complete sentences
 4a)
Physics Talk
 Waves Transfer Energy
  Copy the following sentences in your science notebook.
                                 _________
1. A __________ is a transfer of energy with no net
        wave
   transfer of mass.
2. The energy moving along the spring came from
                                    arms
   chemical energy stored in your _______.
3. Energy is always ____________ .
                      conserved
                             medium
4. The coiled spring is the _____________ through
   which the wave travels and through which energy is
   transferred.
Physics Talk
5. For water waves, the medium is __________________.
                                   the surface of water
6. As waves pass each other, they ______ as they pass.
                                  add
                          travel
  Then they continue to ________ as if the other wave
  had never been present.
Physics Talk
 Vocabulary
Write the definitions to the following in your science
 notebooks.
1. periodic wave
2. crest                      8. transverse wave
3. trough                     9. compressional wave
4. amplitude                  10. standing wave
5. wavelength                 11. node
6. frequency                  12. antinode
7. period
Physics Talk
 Draw and label a diagram showing the parts of a wave.
 Include
   wavelength
   amplitude
   crest
   trough
Physics Talk
 Draw and label the parts of a standing wave with three
 antinodes and four nodes. Label the nodes and
 antinodes, as well as the wavelength.
Physics Talk
 For the sound wave below, label compressions and
 rarefactions. Also, graph the compressions as crests
 and rarefactions as troughs of the wave.
Physics Talk
 ( Compressional / Transverse ) waves on a coiled
  spring are similar to sound waves in air.
 Sound is transferred through air by ______________ it
  and __________________ it.
 The speed of a wave is found by the following formula
       speed = distance traveled / time elapsed
 In symbols,
  v = d/ t
Interference
   When two waves travel through the same space,
    INTERFERENCE occurs.
   The AMPLITUDE of the wave may be determined
    from the SUPERPOSITION of the individual
    amplitudes.
Types of Interference
  If the amplitudes are in the SAME direction
   (aligned), the amplitudes are added and the
   interference is said to be CONSTRUCTIVE.

  If the amplitudes are in OPPOSITE directions, the
   amplitudes are subtracted and the interference is
   said to be DESTRUCTIVE.
Constructive Interference
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Constructive Interference
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        The amplitude of the superposition is
        GREATER than that of the two original
   -6
Destructive Interference
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Destructive Interference
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        The amplitude of this wave is LESS
        than that of the two original waves
   -6
Destructive Interference
 If the amplitudes of the waves are equal in magnitude
 and out of phase by half a wavelength (/2),
 perfect destructive interference occurs.
Destructive Interference
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   +4
        /2

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          
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Destructive Interference
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        -2   -2
   -4             The amplitude of the
                  superposition is
   -6             ZERO
Demonstration with
Sound Waves
 Constructive and destructive interference with stereo
 sound.
Wave Pulses
 Wave pulses pass through one another, interfering
 constructively or destructively during the time they
 occupy the same space.

 Demonstration with slinkys or ropes.
Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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Wave Pulses
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