Up until now, I didn't explicitly mention it, but I used
'to the right' is positive x
and
'to the left' is negative x
so....... seems like we have a problem here...
I think the correct value for the phase is
φ = 0.3948 rad
and NOT
φ = 5.8884 rad
Now... I'm only human, so perhaps I made a mistake somewhere, but...
Just to be sure, I also made a graph of the function:
http://i46.tinypic.com/155296v.png
You can see that at time t=0, the blue graph is still moving away from equilibrium whereas at that time the red graph is moving towards equilibrium.
Perhaps someone else can point out where I went wrong, but until then, I persist in the right answer being:
φ = 0.3948 rad
Edit:
I would really appreciate it if you let me know if I am right here, or... if I'm wrong, then what exactly did I do wrong ;-)
Thanks.