# Phase angle of a string

1. Apr 5, 2008

### physicsgrouch

A transverse, sinusoidal wave is traveling along a string. It moves in the negative x-direction, and it has an amplitude of 5 cm. At time t=0, the point at x=0 is at a displacement of 4 cm and is traveling upward. What is the phase angle in degrees?

2. Relevant equations
x = A*cos($$\omega$$*t+$$\phi$$)

3. The attempt at a solution

At t=0, $$\omega$$*t = 0, so x = A*cos($$\phi$$). Therefore, $$\phi$$ = arccos(x/A) = arccos(.8) = 36.87.

The acceleration is negative and the velocity is positive, so the angle is 360 - 36.87 = 323.13 degrees, right?

2. Apr 6, 2008

### physixguru

The equation you just used is not trustworthy for waves.It can be only generalized to SHM.

You must use wave equations to be more sure in your answers.

y= A sin ( k*x-omega*t + phase angle)