Finding coordinates of a point on an out of phase wave

[tron_2.0]

Hello:

Whats up guys? I haven't posted here in a little while, and after a long summer I've become a bit rusty on my physics so I am going to need a little help from you guys if possible.

Homework Statement

Consider the sin wave of example 13.2 (see below for more info) with the wave function:

y=(15.0cm)cos(0.157x-50.3t)

At a certain instant, let point A be at the origin and point B be the first point along the x-axis where the wave is 60.0 degrees out of phase with point A. What is the coordinate of point B?

In example 13.2 the wave is characterized by:
Amplitude=15.0cm
Wavelength=40.0cm
Frequency=8.00Hz

Homework Equations

k=2pi/lamda
T=1/F
omega=2pi*f
v=f*lamda

The Attempt at a Solution

i really think I am overthinking this problem, if the wave is pi/3 radians out of phase, wouldn't that be our phase constant? and from there, how would i turn a function of y(x,t) into y(x) by holding t constant? like how would the equation I've written be changed so i can find the proper coordinate?

 

[tron_2.0]

helpppp! haha

 

[tron_2.0]

up up up up up please i need help asap =[

 

[alphysicist]

Hi tron_2.0,

If the problem had asked for the point that was 360 degrees out of phase with the point at the origin, what would the x-coordinate of that point be? What about the point that is 180 degrees out of phase? Does that help?

 

[tron_2.0]

Hi tron_2.0,

If the problem had asked for the point that was 360 degrees out of phase with the point at the origin, what would the x-coordinate of that point be? What about the point that is 180 degrees out of phase? Does that help?

in that case wouldn't out conrtolled variable (x) be 2pi for 360 degrees and pi for 180 degrees? and after that couldn't we plug pi or 2pi into the equation for y(x) i gave above? i was thinking that but i don't know if that's right. and if that is true, what happens to t?

 

[alphysicist]

in that case wouldn't out conrtolled variable (x) be 2pi for 360 degrees and pi for 180 degrees? and after that couldn't we plug pi or 2pi into the equation for y(x) i gave above? i was thinking that but i don't know if that's right. and if that is true, what happens to t?

I was thinking of a more straightforward answer, based just on what you know about this wave. Compared to the wave at the origin, x=0m, what x value in meters is 360 degrees (or 2pi radians) apart in phase?

Based on how that works, you should be able to find the x coordinate of the point you are looking for with a simple ratio.

(You don't have to worry about the time, since at the beginning of the problem they say find everything "At a certain instant". Just set t to a specific value, and setting it to t=0 is easiest.)