What is phase constant

  1. Feb 10, 2012 #1
    I just started learning Simple Harmonic Motion and encountered a word Phase Constant [itex]\phi[/itex] .
    Actually it appeared as
    f(t)=rsin([itex]\omega t+\phi[/itex])
    I am confused whether phase constant is actually the initial position of the particle(which execute SHM) and therefore the point on graph at time=0 or not!!!
  2. jcsd
  3. Feb 11, 2012 #2


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    welcome to pf!

    hi justwild! welcome to pf! :wink:

    you're right, the phase constant is the initial angle (or initial phase): the angle (or phase) at t = 0 :smile:
  4. Feb 11, 2012 #3
    what is the harm if we just take [itex]\omega t[/itex] as the argument.
  5. Feb 11, 2012 #4


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    You just shift the motion in phase slightly. All te same key features are there.
  6. Feb 11, 2012 #5
    If [itex]\phi[/itex] is the initial angle then I think the sinusoidal graph will show different starting points(t=0) for different values of [itex]\phi[/itex] of the same amplitude and frequency of vibration. Is that so???
  7. Feb 11, 2012 #6


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    you can eliminate the phase constant by changing the starting time …

    if you replace t by t + φ/ω, then the phase constant is zero :smile:
    not following you :confused:
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