Wave problem It's been driving my crazy for last hour

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The discussion revolves around solving a wave problem involving a transverse wave on a string. For part A, the participant attempts to find the velocity of propagation using the wave equation y(x,t) = Acos(2π(kx - wt)), but struggles with the concept of velocity of propagation. In part B, they analyze two traveling waves with given parameters to derive the standing wave function, but their calculated values for amplitude, wave number, and angular frequency are incorrect according to the feedback from Mastering Physics. The correct answers for part B are ultimately provided as 4.92×10−3 m for amplitude, 15.5 1/m for k, and 1720 1/s for W. The discussion highlights the challenges in applying wave equations and the importance of accurate unit conversions and calculations.
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Wave problem! It's been driving my crazy for last hour!

Homework Statement


A)
Wave motion is characterized by two velocities: the velocity with which the wave moves in the medium (e.g., air or a string) and the velocity of the medium (the air or the string itself).

Consider a transverse wave traveling in a string. The mathematical form of the wave is y(x,t) = Acos2pi(kx-wt)

Find the velocity of propagation Vp of this wave.
Express the velocity of propagation in terms of some or all of the variables A, k, and W.

B)Two traveling waves move on a string that has a fixed end at . They are identical, except for opposite velocities. Each has an amplitude of 2.46 mm, a period of 3.65 ms, and a speed of 111 m/s.

The wave function of the resulting standing wave has the form y(x,t)=Asin(kx)sin(wt). Give the values of A, k, and W. Use meters (m) for A, inverse meters (1/m) for k, and inverse seconds (1/s) for W.




Homework Equations


A)
I believe I should use y(x,t) = Acos2pi(kx-wt)
B)
A is given
W=2(pi)f where f = 1/T
K = w/v

The Attempt at a Solution



A)
Ok so to find the velocity, we take the partial derivative and get
dy/dt = wAsin[kx-wt]

And I thought that was the answer but apparently it wasn't.

What is the velocity of propagation anyways? Maybe that's where I need to start.

B)
This one, I thought I had it right but apparently, Mastering Physics has been telling me its not.

Amplitude's given, so just convert 2.46mm to meters.

W(Omega) can be simply found by the equation w = 2pi/T

And since velocity is given, we can just plug that value in into k = w/v and find the wave number.

I got 2.46*10^-3 as Amplitude, 1720 for W and 15.5 for k and the program's telling me its wrong.

Am I tackling the problem wrong?

Any help would be deeply appriciated
 
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Can anyone help with this? I too have been trying to figure it out, only part B.
 


For the record, the answer turned out to be:

4.92×10−3, 15.5, 1720
 
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