# What is phase constant

1. Feb 10, 2012

### justwild

I just started learning Simple Harmonic Motion and encountered a word Phase Constant $\phi$ .
Actually it appeared as
f(t)=rsin($\omega t+\phi$)
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. Feb 11, 2012

### tiny-tim

welcome to pf!

hi justwild! welcome to pf!

you're right, the phase constant is the initial angle (or initial phase): the angle (or phase) at t = 0

3. Feb 11, 2012

### justwild

what is the harm if we just take $\omega t$ as the argument.

4. Feb 11, 2012

You just shift the motion in phase slightly. All te same key features are there.

5. Feb 11, 2012

### justwild

If $\phi$ is the initial angle then I think the sinusoidal graph will show different starting points(t=0) for different values of $\phi$ of the same amplitude and frequency of vibration. Is that so???

6. Feb 11, 2012

### tiny-tim

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
not following you