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**1. Homework Statement**

An object is undergoing SHM with period 0.9 s and amplitude 0.32 m. At t=0, the object is at x=0.32 m and is instantaneously at rest. Calculate the time it takes the object to go from 0.32 m to 0.16 m, and to go from 0.16m to 0 m.

**2. Homework Equations**

x=Acos(wt+θ)

f=1/T

w=2∏f

**3. The Attempt at a Solution**

I completely understood the first part of the problem when going from x= .32 to x= .16. using the formulas to come up with the angular frequency and then just solving for t, in which i got the answer t= 0.15 s.

I'm confused about the second part because it isn't starting from t=0. I was thinking that the only difference in the formula would be the phase angle, i just don't understand how to come up with that. i thought that the phase angle is the angle in which x is at the position you are starting at, if you start at a position .16 m with an unknown t-value, how do you know what the phase angle is?