Physics 6 Waves

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Physics 6 Waves
2013-09-09 18:06:59
Physics waves

Physics 6 waves
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  1. Define: Wave and types
    • Wave: transfer of momentum and energy from one point to another
    • Types: Mechanical, Electromagnetic, and matter
  2. What are two types of mechanical waves?
    Transverse and longitudinal
  3. Define: wavelength, Frequency, period, and amplitude. Give units
    • wavelength (lambda): distance between two identical (repeated) points in a wave (meters)
    • Frequency (f): the amount of waves that pass a point in space in 1 sec (m/s=Hz)
    • Period (T): recipricol of frequency - time/wavelength
    • Amplitude (A): Maximum displacement from 0 (always positive)
  4. What are the two big rules for waves?
    • 1: the speed of a wave is determined by the medium and type of wave.  NOT frequency.  Frequency is inversely propoprtional to wavelength in any given medium
    • 2:When a wave transfers between mediums, the velocity changes, but the frequency does not
  5. Equation for velocity of a wave.
    • v=fV
    • f=frequency
  6. 2 aspects of media that affect the velocity of a wave
    • 1: elasticity/resistance to change in shape
    • 2:inertia/resistance to change in motion
  7. how do decibels work?
    They are a logrithmic representation of sound intensity that create an intuitive scale.

    every factor of 10 change in intensity is equivilent to an addition/subraction of 10 decibels.  300 to 3000 is 10 decibels, 10-10000 is 30 decibels
  8. define:phase, constructive and destructive interference
    • phase: is kind of an address for a wave.  It describes its wavelength, frequency, and place in time against its origin.
    • constructive: when 2 or more waves superimpose and the sum of their displacements are larger
    • deconstructive: when 2 or more waves superimpose and the sum of their displacements are smaller
  9. Describe simple harmonic motion
    Any motion that is repetitious and resembles a sine wave as a function of time
  10. 3 properties to be aware of in simple harmonic motion
    • 1: Acceleration is directly proportional to displacement, but opposite in sign.
    • 2: Acceleration and displacement are related byu the square of the frequency
    • 3: energy of a system in simple harmonic motion oscillates between kinetic and potential energy.
  11. Define: doppler effect
    because sound waves move at speeds independently of the speed of what created them, the frequency of the wave experienced by a stationary observer changes with the distance it travels and is therefore experienced differently although it is the same wave.
  12. equation for Decibels
  13. Give equation for nodes of standing wave
    • L=[n(lambdan)]/4 (n=odd positive integers)
    • L=[n(lmabdan)]/2 (n= all positive integers)
  14. what is the equation for beat frequency
    fb=|f- f2|
  15. Doppler effect equations
    • [(delta)f/fs] = v/c
    • [(delta)(lambda)/(lambdas) = v/c