How can I find the value of phi in a simple harmonic motion equation?

AI Thread Summary
To find the value of phi in a simple harmonic motion equation, start by analyzing the displacement formula and its first derivative, which gives the velocity equation. The correct form of the velocity equation is v = -Aωsin(ωt + φ). To determine phi, evaluate the function at t=0 and analyze the graph to identify the phase offset. Understanding that phi represents the initial phase shift can help clarify its value. This approach will guide you in solving for phi effectively.
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http://noether.physics.ubc.ca/physics153/assign72k5.pdf

I don't get number 1 c, which equation do i use? and in general, how would I be able to find phi?

OK, i figured i should find the first derivative of the displacement formula, which becomes v = -Asin(wt + phi) but that still undoable, how do i find phi?
 
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Check your derivative. remember that max(sin(x)) is 1
 
ah yes, i see, it should be v = -A ωsin(ωt + φ), but that's just a typo, i actually had this equation when i wrote it down on paper. But i still don't know how to find phi
 
look at t=0 ... what's the function? what's the graph?
phi is just the "little wt offset" if you don't start the timer in synch.
 
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