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Finding wavelength and wave speed in a sinusoidal wave. 
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#1
Dec511, 03:38 PM

P: 82

1. The problem statement, all variables and given/known data
A sinusoidal wave is propagating along a stretched string that lies along the xaxis. The displacement of the string as a function of time is graphed in the figure (attachment) for particles at x=0m and x=0.0900m. (A) What is the amplitude of the wave? 4mm (B) What is the period of the wave? 0.04s I am confused by the following questions: (C) You are told that the two points x=0 an x=0.09m are within one wavelength of each other. If the wave is moving in the +xdirection, determine the wavelength and wave speed. ANSWER KEY: 0.14m and 3.5m/s (D) If the wave is moving in the xdirection, determine the wavelength and wave speed. ANSWER KEY: 0.24m and 6.0m/s 2. Relevant equations y(x,t)=Acos(kx +/ ωt) v=λf 3. The attempt at a solution Initially I thought the wavelength would be 0.09 since it says 0 and 0.09 are one wavelength away from each other... But then I looked at the answer key and it seems my interpretation is wrong. Does anyone know what the question is asking in C? 1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution 


#2
Dec511, 08:53 PM

HW Helper
P: 3,394

It doesn't say 0 and .09 are one wavelength apart.
If they were, they would peak simultaneously. It looks like one peaks about .025 s after the other. That would mean the wave went one wavelength in time .025. Can you get a wavelength or velocity out of that? If you get one, you can find the other with the wave equation. 


#3
Dec511, 10:15 PM

P: 1,368

.09m/.025s or .09m/.015s ? Confusing graph at first. 


#4
Dec511, 10:45 PM

P: 82

Finding wavelength and wave speed in a sinusoidal wave.
But yeah I think he is correct, it took 0.025s to travel from 0m to 0.09m, so the velocity is about 3.6m/s and wavelength is 0.144m. 


#5
Dec511, 10:52 PM

P: 82

Oh I see because we start at x=0.
Thanks for the help! 


#6
Sep812, 11:33 PM

P: 1

Im a little confused on why the wavelength is different when the wave is moving in the x direction. Can somebody shed a little light in this for me?



#7
Sep912, 06:06 AM

P: 1,368

Hope this was helpful. Good luck. 


#8
Sep2212, 12:19 PM

P: 1,368




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