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1. Prove that y(x,t) = Ae-i(kx-?t) is a solution to the wave equation. In other

ID: 2101145 • Letter: 1

Question

1.    Prove that y(x,t) = Ae-i(kx-?t) is a solution to the wave equation. In other words, you should end with v = ?/k.


2.    For the function y(x,t) = 7cm sin[?(x/4cm + t/6s) find the following:
a.    What are the frequency, wavelength, and amplitude?
b.    What is the velocity of the wave?
c.    What is the direction of propagation?


3.    Explicitly write out the standard form for a wave that is traveling in the +x direction and has a frequency of 200 Hz, a wave velocity of 400m/s, and an amplitude of 0.1m.


4.    With what tension must a rope with length 2.50 m and mass 0.12 kg be stretched for transverse waves of frequency 40.0 Hz to have a wavelength of 0.75 m?

Explanation / Answer

y(x,t) = Ae-i(kx-?t)

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?y/?t = Ai?e-i(kx-?t)

?2y/?t2 = A(i?)(i?)e-i(kx-?t) = -A?2 e-i(kx-?t)

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?y/?x = -Aike-i(kx-?t)

?2y/?x2 = A(-ik)(-ik)e-i(kx-?t) = -Ak2 e-i(kx-?t)

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wave equation:

?2y/?t2 = v2 ?2y/?x2

>>>> -A?2 e-i(kx-?t) = v2 (-Ak2 e-i(kx-?t))

>>>> ?2 = v2 k2

>>>> ? = v k

>>>> v = ?/k

>>>> proved!   


2.A.The frequency of the wave is