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What does the phase angle phi mean in the harmonic oscillation function?

  1. Oct 10, 2012 #1
    The function for simple harmonic oscillation is:
    Acos(ωT)+[itex]\phi[/itex]
    Why is there an angle phi added to the function acos(ωT)?
     
  2. jcsd
  3. Oct 10, 2012 #2
    it's Acos(ωT+ϕ) omega stands for how fast it' s oscilating, but phi determines the initial position( wold be Acosϕ)
     
  4. Oct 10, 2012 #3
    I was reading a book on wave and found that when they derive the equation of shm from the equation force varies with negetive displacement , they had taken a propotionality constant to make the force and displacement equal and they had taken frequency of the shm as the constant . So my question is , is there any derivation which can show that the constant is the frequency of the shm .
     
  5. Oct 10, 2012 #4
    If phi had a value, what would the shm graph look like? Or how would it change from Acos(wT)?
     
  6. Oct 11, 2012 #5
    The graph would change from sine to cosine, (remember, that sin(x+π)=cosx)
     
  7. Oct 11, 2012 #6
    isnt the function already Acos(wT)+phi?
     
  8. Oct 11, 2012 #7
    so how could it change from sine if it doesnt start at sine?
     
  9. Oct 11, 2012 #8
    It never started as cosine, it's allways either sine or cosine or somethin in between. It's like you move the cosine a bit to the right and if you move it by π/2 you get sine! SO all phi determines is the initial position!
     
  10. Oct 12, 2012 #9
    Ok... Thanks! I almost understand.
     
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