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Integrated Coordinated Science for the 21st Century

Active Physics
+ Chapter 4
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  1. a) amplitude: measure the distance of a point on the spring from its rest position.
    wavelength: make a standing wave; measure the distance between the points of the spring that do not move; twice this distance is the wavelength.
    frequency: measure how many times you shook the spring in ten seconds and divide by ten.
    speed: make a pulse; measure distance traveled and time elapsed; divide time into distance to find the speed.
    b) amplitude and wavelength: meters
    frequency: 1/s (Hz)
    speed: m/s
    c) Speed is frequency times wavelength.
  2. a) When you shake the spring more rapidly, you can see more crests and the crests are closer together. If you are making standing waves, the more rapidly you shake the spring, the more complete waves you will see.
    b) The wavelength and frequency change.
    c) The speed does not change.
  3. If there is a meter stick in the photograph, use its image to measure the distance between one crest and the next.
  4. Measure the time for a point on the spring to go through one complete cycle. You may have to measure for ten cycles and divide the time by ten.
  5. a) m
    b) 1/s
    c) m/s
    d) speed = wavelength X frequency
    e) m/s = m X 1/s
  6. a) A standing wave is a repeating back-and-forth motion that does not move from one place to another. For transverse waves on a Slinky, the parts of the spring move from side-to-side, but nothing moves along the spring (nothing moves like the pulse did).
    b) See diagram on page 185.
    c) See diagram on page 184.
    At places where the wave amplitude is zero, there is no wave motion. At other places, the wave amplitude increases, reaches a maximum, then decreases, goes through zero, changes sign, reaches
    a maximum, goes back through zero, etc.
    d) Find the length of one complete wave of the spring. Or, figure out what fraction of a wave you see on the spring and from that compute the wavelength.
  7. a) In a compressional wave, the back-and-forth motion is in the same direction that the disturbance moves (or in the opposite direction). In a transverse wave, the back-and-forth motion is perpendicular to the direction the disturbance moves.
    b) In transverse waves, the Slinky moves back-and-forth perpendicular to its length. In compressional waves, the Slinky moves back-and-forth along its length.
  8. a) You shook the spring at a higher frequency.
    b) You shook the spring at a lower frequency.
  9. If the speed of the wave seen with the viewer increases, the frequency increases but the wavelength remains the same. If these were water waves and you photographed them, the wavelength would remain the same no matter what the speed of the wave (you could measure the wavelength from a still photo). But if you made a video, you would see more crests go by if the wave speed increased. That is consistent with the relationship speed = wavelength X frequency.