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## Homework Statement

What is the phase constant (from 0 to 2π rad) for the harmonic oscillator with the velocity function v(t) given in Fig. 15-30 if the position function x(t) has the form x = x

_{m}cos(ωt + φ)? The vertical axis scale is set by vs = 7.50 cm/s.

[PLAIN]http://img227.imageshack.us/img227/4729/qu1512.gif [Broken]

## Homework Equations

x = x

_{m}cos(ωt + φ)

v=-ωx

_{m}sin(ωt + φ)

v

_{m}=ωx

_{m}

## The Attempt at a Solution

From graph, v

_{m}=9.375 cm/s

v

_{m}=9.375 cm/s = ωx

_{m}

x

_{m}=9.375/ω

At t=0, v(0)=7.5 cm/s=-ωx

_{m}sin(φ)

φ=sin

^{-1}(7.5/-ωx

_{m})

φ=sin

^{-1}(7.5/-ω*9.375/ω)

φ=sin

^{-1}(7.5/-9.375)= -.927 rad

I still got it wrong and not sure where I messed up. Only thing that I can think of is that I incorrectly assumed t=0 is 7.5 cm/s and if that's the case then I don't know where to begin on this problem.

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