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## Homework Statement

The figure shows the displacement

*y*versus time

*t*of the point on a string at

*x*= 0, as a wave passes through that point. The scale of the

*x*axis is set by

*ys*= 84.0 mm.The wave has form

*y*(

*x, t*) =

*ym*sin (

*kx*-

*ωt*+

*φ*). What is

*φ*? (

*Caution:*A calculator does not always give the proper inverse trig function, so check your answer by substituting it and an assumed value of

*ω*into

*y*(

*x, t*) and then plotting the function.)

## Homework Equations

*y*(

*x, t*) =

*ym*sin (

*kx*-

*ωt*+

*φ*)

## The Attempt at a Solution

This is supposed to be really easy but the solution I got was wrong. My approach was straight forward:

read off the initial y value --- y(0,0)=0.028

and sub in the equation: 0.028=0.084sin(0-0+

*φ*)

*φ=arcsin(0.028/0.084)=0.339836...=0.340 rad*

The question mentioned that the calculator might give the wrong value but I do not see how I could make amend to it.

Please enlighten me!