phase constant of SHM

1MileCrash

1. The problem statement, all variables and given/known data

The displacement of a mass oscillating on a spring is given by x(t) = xmcos(ωt + ). If the initial displacement is zero and the initial velocity is in the negative x direction, then the phase constant is:

2. Relevant equations



3. The attempt at a solution

How do I start? The book just tells me that the phase constant depends on displacement and velocity when t = 0, but doesn't say how.

gneill

Sketch a cosine curve. What's its initial value? Where on the curve would match the initial condition of the spring and mass? What's (angular) the offset from zero?

1MileCrash

OK

1

Huh??

gneill

Does the mass start at a maximum extension like the cosine function does?

1MileCrash

No, initial displacement is 0. So, I need to find where cosx equals 0?

gneill

Not only that, but where it's going through zero and going negative, just like the mass' displacement.

1MileCrash

Still have no clue on this.

gneill

Have a gander:

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